**Colonoscopy Screening for Colorectal Cancer — Overview of the Literature**

Carlos Eduardo Pinzon-Florez, Oscar Andres Gamboa-Garay and Diana Marcela Diaz-Quijano

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/61851

#### **Abstract**

Objective: The aim of our chapter was to perform a systematic review of the clinical practice guidelines, randomized clinical trials, and prospective studies, using total colonoscopy for screening this population for colorectal cancer (CRC) and to evaluate the effectiveness of diagnosis and safety.

Methods: We included clinical practice guidelines, systematic reviews, and pri‐ mary studies with more than 25 participants, and only those reporting the evaluation of colonoscopy as screening test for colorectal cancer and adenoma were included in this chapter. Analysis was performed for three outcomes: ac‐ curacy of colonoscopy as a screening test, reduction of colorectal cancer inci‐ dence and prevalence, and identification of adverse events of the procedure.

Results: For screening colonoscopy, evidence was of moderate quality. The evi‐ dence results suggest tentatively an even stronger reduction in distal colorectal cancer incidence and mortality. The colonoscopy significantly reduces the mor‐ tality for CRC. These studies suggest a 17% to 30% lower risk of incident color‐ ectal cancer and 64% death from colorectal cancer after screening colonoscopy vs other screening diagnosis tests.

Conclusions: Colonoscopy is a feasible and safe method for screening CRC for proximal locations in asymptomatic people; however, these findings must be in contrast with the cost of the procedure, accessibility opportunities, and com‐ plications.

**Keywords:** Colonoscopy, Screening, Colorectal cancer, Adenoma, Fecal occult blood test (MeSH terms)

© 2015 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

## **1. Introduction**

#### **1.1. Epidemiology of colorectal cancer**

#### *1.1.1. The colorectal cancer worldwide*

Colorectal cancer is a disease typical of the regions with the largest urban and industrial development, which has changed consumption patterns and life. Worldwide, the rate of ageadjusted incidence (APR) of 17.2 cases per 100,000, ranking fourth in incidence among all types of cancer in both sexes, is presented, with a higher incidence rate in men than in women, APR of 20.3 and 14.6 cases per 100,000, respectively, for a total of 663,000 cases in men and 571,000 cases in women (1). About 60% of these cases occur in developed regions; the highest incidence rates are found in Australia, New Zealand, and Western Europe and the lowest in Africa (excluding South Africa) and South-Central Asia, with intermediate rates in Latin America (1).

Worldwide, the mortality rate adjusted for age (TAE) of colorectal cancer is 8.2 cases per 100,000, being the fifth leading cause of cancer death in both sexes, following lung, breast, stomach, and liver cancer. In men, it is 9.6 cases per 100,000 and for women, it is 7.0 cases per 100,000 (being the fourth most common type in both men and women). Nearly 608,000 deaths per year from colorectal cancer are presented, accounting for 8% of all cancer deaths. Unlike the cases of incidence, the highest mortality rates in both sexes are presented in Central and Eastern Europe (20.1 per 100,000 for men, 12.2 per 100,000 for women) and lower mortality rates are presented in Central Africa (3.5 per 100,000 for men and 2.7 per 100, 000 for women) (1).

The diagnosis is made predominantly with the location of polyps, 92% of them in situ and 40 % of cases are diagnosed at 60 years of age, 30 % at 50, and 30 % at 70. The rest 95 % of diagnoses shows adenocarcinoma type as the predominant pathology, being 80 % of sporadic nature, over the diagnosis of hereditary familial problem like. Less than 3% of patients are under 40 years (2).

Colon and rectal cancer have been associated with various risks, such as chronic ulcerative colitis; sclerosing cholangitis; certain inherited problems; a number of aspects related to eating habits, such as low-residue diet rich in saturated fats, diabetes, obesity, lack of physical activity, low intake of fruits and vegetables, smoking, and alcohol intake; ethnicity; and other genetic factors. However, only age has been measured in quantitative terms to establish the burden attributable to mortality. It is also necessary to specify, through additional studies, the burden of risk factors such as familial adenomatous polyposis, hereditary polypoid colorectal cancer, inflammatory bowel disease, sclerosing cholangitis, and others (2, 3).

Due to many factors, probably related to health technologies and early detection of the problem, among others, in the last 20 years, overall survival increased from 42 to 62 %. According to data in Globocan 2008, the five-year survival can be 72 % in men and 61 % in women (1, 2).

#### **1.2. Colonoscopy and screening**

**1. Introduction**

**1.1. Epidemiology of colorectal cancer**

4 Screening for Colorectal Cancer with Colonoscopy

Colorectal cancer is a disease typical of the regions with the largest urban and industrial development, which has changed consumption patterns and life. Worldwide, the rate of ageadjusted incidence (APR) of 17.2 cases per 100,000, ranking fourth in incidence among all types of cancer in both sexes, is presented, with a higher incidence rate in men than in women, APR of 20.3 and 14.6 cases per 100,000, respectively, for a total of 663,000 cases in men and 571,000 cases in women (1). About 60% of these cases occur in developed regions; the highest incidence rates are found in Australia, New Zealand, and Western Europe and the lowest in Africa (excluding South Africa) and South-Central Asia, with intermediate rates in Latin America (1).

Worldwide, the mortality rate adjusted for age (TAE) of colorectal cancer is 8.2 cases per 100,000, being the fifth leading cause of cancer death in both sexes, following lung, breast, stomach, and liver cancer. In men, it is 9.6 cases per 100,000 and for women, it is 7.0 cases per 100,000 (being the fourth most common type in both men and women). Nearly 608,000 deaths per year from colorectal cancer are presented, accounting for 8% of all cancer deaths. Unlike the cases of incidence, the highest mortality rates in both sexes are presented in Central and Eastern Europe (20.1 per 100,000 for men, 12.2 per 100,000 for women) and lower mortality rates are presented in Central Africa (3.5 per 100,000 for men and 2.7 per

The diagnosis is made predominantly with the location of polyps, 92% of them in situ and 40 % of cases are diagnosed at 60 years of age, 30 % at 50, and 30 % at 70. The rest 95 % of diagnoses shows adenocarcinoma type as the predominant pathology, being 80 % of sporadic nature, over the diagnosis of hereditary familial problem like. Less than 3% of patients are under 40

Colon and rectal cancer have been associated with various risks, such as chronic ulcerative colitis; sclerosing cholangitis; certain inherited problems; a number of aspects related to eating habits, such as low-residue diet rich in saturated fats, diabetes, obesity, lack of physical activity, low intake of fruits and vegetables, smoking, and alcohol intake; ethnicity; and other genetic factors. However, only age has been measured in quantitative terms to establish the burden attributable to mortality. It is also necessary to specify, through additional studies, the burden of risk factors such as familial adenomatous polyposis, hereditary polypoid colorectal cancer,

Due to many factors, probably related to health technologies and early detection of the problem, among others, in the last 20 years, overall survival increased from 42 to 62 %. According to data in Globocan 2008, the five-year survival can be 72 % in men and 61 % in

inflammatory bowel disease, sclerosing cholangitis, and others (2, 3).

*1.1.1. The colorectal cancer worldwide*

100, 000 for women) (1).

years (2).

women (1, 2).

For about two decades, multiple reports of epidemiological studies have concluded that the introduction of endoscopic procedures is effective for strippage of premalignant lesions. The number of countries that have included colonoscopy and sigmoidoscopy as screening strategies for CRC has increased; however, the cost of implementation and potential adverse events limited its use for those in the middle- and low-income population (1-3).

It is clear that in populations at high risk of colorectal cancer (hereditary familial polyposis, ulcerative colitis or Crohn's disease), the screening test of choice is colonoscopy (4-5). Likewise in early detection in the general population, testing fecal occult blood is implemented and after a positive result, confirmatory colonoscopy and treatment is performed, which seeks to remove the precancerous lesion or cancer in situ. Colonoscopy does not fully meet the criteria on being a screening test for CRC because it is expensive; however it has some advantages because it can include treatment of polyp lesions and early cancer; unfortunately, only few studies of controlled trials have been conducted to analyze the performance of colonoscopy as a screening test for CRC. With regard to sigmoidoscopy, the advantages presented are the evaluation of the proximal colon, and only sigmoidoscopy can assess the distal colon, where most cancers occur [6]. Compared to testing fecal occult blood, colonoscopy has a major role in terms of reducing the incidence and mortality of CRC (7); Winawer and colleagues demonstrated a decrease in CRC incidence – 70 to 90 % – in a cohort of 1400 patients after polypectomy compared with controls based on symptoms and physical examination (8,9). In a study in Olmsted County, a decline in annual mortality of 25.2/100,000 to 21.4/100,000 followed the increase at subsequent rate of polypectomies (10).

The objective of this chapter is to review the literature and make some conclusion about total colonoscopy for screening CRC and the complication rate of screening colonoscopy in this setting, particularly bleeding, perforation, and death.

#### **2. Methods**

The purpose of this review is to evaluate the effectiveness and safety of colonoscopy as a screening test for adenoma, advanced adenoma, and colorectal cancer. For safety outcome, we evaluated bleeding, perforation, and death.

An asymptomatic person is defined as a person over 40 years and less than 75 years old without abdominal pain, rectal bleeding, weight loss, or changes in bowel habits.

Early and late adenomas were defined as adenomas smaller than 10 mm and greater than 10 mm, respectively, both of villous adenoma histology or high-grade dysplasia.

#### **2.1. Data source and search strategy**

We made a literature search in MEDLINE, EMBASE, the Cochrane Library, CINAHL, and LILACS from 1966 to February 2015. On the other hand, we made a search of guidelines in the websites of the developer groups NICE, New Zealand Group, SIGN, North America Centers, IETS in Colombia, and CENETEC in Mexico, using the following keywords: ''screening colonoscopy,'' "colonoscopy," "colorectal cancer," "polyps," and ''screening colorectal cancer.'' The types of secondary studies were systematic reviews of the literature and clinical practice guidelines. The primary study types were controlled clinical trial, observational cohort, and case-control studies. Studies published in Spanish and English were the only ones selected. Likewise, additional searches were made from bibliographies of studies identified in the initial search.

#### **2.2. Study selection**

The clinical practice guidelines that were rated with 2 older AGREE (11) 60% quality in the domain of methodology were included. Systematic reviews of the literature described colonoscopy as a screening strategy. For primary studies such as controlled trials and obser‐ vational analytical studies of moderate to high quality, we included the checklists of SIGN (12).

Exclusion criteria was studies evaluating colonoscopy in high-risk population of CRC, other studies evaluating screening tests without comparison with colonoscopy, likewise studies that do not contemplate the outcomes of interest for this chapter and not to report measures were considered effect with confidence intervals

#### **3. Results**

#### **3.1. Evidence that exists for screening colorectal cancer**

Screening is the examination of asymptomatic individuals or healthy individuals in order to classify them as likely or unlikely to have a disease (6).

The standard screening test is colonoscopy, but there are alternatives such as flexible sigmoi‐ doscopy, computed tomography colonography (CTC or virtual colonoscopy) (7), fecal occult blood test (FOBT) or stool analysis, and also, evidenced by the literature, combined sigmoi‐ doscopy and FOBT; the alternatives also include barium enema and endoscopy capsule; however, there are insufficient epidemiological studies that support these types of screening (8-15).

The optimal strategy of screening for colorectal cancer is selected considering the following criteria: age of onset and age range in individuals at average risk for this condition.

#### **3.2. Volume of evidence**

For this issue, three clinical practice guidelines were included that scored highly in method‐ ology dimension with the AGREE2 checklist: quality assurance in colorectal cancer screening and diagnosis of the IARC (5) Screening for Colorectal Cancer, US Preventive Services Task Force (USPSTF) recommendation statement (17), and a clinical practice guideline for the early detection, diagnosis, treatment, following, and rehabilitation of patients with colorectal cancer of the Colombian Ministry of Health (18).

The review process identified 22 systematic reviews of which six were contained in guidelines previously described (19-24). Of the 16 remaining systematic reviews, two publications were discarded because they did not have clarity in the average-risk population (25; 26) and five for lack of data for the average-risk population (27-31).

The remaining nine studies were scored with the GRADE system. According to screening strategies, four publications analyzed fecal occult blood test (32-35) and two conducted a systematic review of colonoscopy (36), two studies evaluated colonoscopy and compared it with CTC (virtual colonoscopy) (37; 38) and another study evaluated only the CTC (39), and the last review examined capsule endoscopy (40). The American GPC (17) includes a strategy of screening using FOBT, sigmoidoscopy, or colonoscopy beginning at age 50 and ending at age 75.

#### **3.3. Colonoscopy**

websites of the developer groups NICE, New Zealand Group, SIGN, North America Centers, IETS in Colombia, and CENETEC in Mexico, using the following keywords: ''screening colonoscopy,'' "colonoscopy," "colorectal cancer," "polyps," and ''screening colorectal cancer.'' The types of secondary studies were systematic reviews of the literature and clinical practice guidelines. The primary study types were controlled clinical trial, observational cohort, and case-control studies. Studies published in Spanish and English were the only ones selected. Likewise, additional searches were made from bibliographies of studies identified in

The clinical practice guidelines that were rated with 2 older AGREE (11) 60% quality in the domain of methodology were included. Systematic reviews of the literature described colonoscopy as a screening strategy. For primary studies such as controlled trials and obser‐ vational analytical studies of moderate to high quality, we included the checklists of SIGN (12).

Exclusion criteria was studies evaluating colonoscopy in high-risk population of CRC, other studies evaluating screening tests without comparison with colonoscopy, likewise studies that do not contemplate the outcomes of interest for this chapter and not to report measures were

Screening is the examination of asymptomatic individuals or healthy individuals in order to

The standard screening test is colonoscopy, but there are alternatives such as flexible sigmoi‐ doscopy, computed tomography colonography (CTC or virtual colonoscopy) (7), fecal occult blood test (FOBT) or stool analysis, and also, evidenced by the literature, combined sigmoi‐ doscopy and FOBT; the alternatives also include barium enema and endoscopy capsule; however, there are insufficient epidemiological studies that support these types of screening

The optimal strategy of screening for colorectal cancer is selected considering the following

For this issue, three clinical practice guidelines were included that scored highly in method‐ ology dimension with the AGREE2 checklist: quality assurance in colorectal cancer screening and diagnosis of the IARC (5) Screening for Colorectal Cancer, US Preventive Services Task Force (USPSTF) recommendation statement (17), and a clinical practice guideline for the early

criteria: age of onset and age range in individuals at average risk for this condition.

the initial search.

**3. Results**

(8-15).

**3.2. Volume of evidence**

**2.2. Study selection**

6 Screening for Colorectal Cancer with Colonoscopy

considered effect with confidence intervals

**3.1. Evidence that exists for screening colorectal cancer**

classify them as likely or unlikely to have a disease (6).

Colonoscopy is undoubtedly useful in the case of positive fecal occult blood test. The European guide (16) describes that there is limited evidence on the effectiveness of colonoscopy screening to reduce colorectal cancer incidence and mortality. Recent studies suggest that colonoscopy may not be as effective in the right colon and in other segments of the colon and rectum. It also indicates that there is limited evidence suggesting that the interval for colonoscopy should be less than 10 years and may even extend to 20 years. The American guide includes colonoscopy as one method of screening for patients with a 10-year interval (17).

Three of the nine appointed guides as a strategy to colonoscopy screening at intervals of 10 years (18, 22, 24). These recommendations on the ability of colonoscopy as a screening strategy in asymptomatic individuals are not supported by controlled clinical trials; only case-control studies suggest that colonoscopy screening is associated with a low incidence of colorectal cancer (OR 0.46 95 % CI: 0.36.9 to 0.57) and that it decreases colorectal cancer mortality (OR 0.44: 95 % CI: 0.31 to 0.62) (13). The Australian guide suggests that for diagnostic confirmation, in the presence of a positive fecal occult blood test, colonoscopy is indicated, in order to perform biopsies of lesions and therapeutic removal of adenomas (20). The meta-analysis of Niv et al. (38) included ten prospective cohort studies with a total of 68,324 participants in which the procedure was completed by 97%. Colorectal cancer was found in 0.78 % of cases (95 % CI: 0.13 to 2.97): 77 % of CRC patients were in stages I and II. Advanced adenomas occurred in 5 % of cases (95 % CI 4–6 %).

The study of Niv et al. (38), found during the update, concludes that colonoscopy is a feasible method of screening for average-risk individuals; however, the GRADE rating was low for all three outcomes reported: colorectal cancer screening, drilling complications, and bleeding complications because the authors did not present the search strategy. The primary results are contradictory, and no evidence of homogeneity is presented. The study of Brenner Hermann et al. (6) includes four randomized clinical trials, eight case-control studies, and four cohort studies; the result for randomized clinical trial studies reports reduction in overall colorectal cancer mortality in 22–31 %; in meta-analysis, the pooled risk reduction for incidence was estimated to be 18 % (CI 95 % 11–25%) and for mortality from colorectal cancer 28 % (CI 95 % 20–35 %). The result of observational studies for distal colorectal cancer was strong in reduced incidence and mortality, reduction of 64 % (CI 95 % 50–74 %) in incidence colorectal rates and 66 % (38–81 %) in reduced mortality rates for cancer (6). In this study, it was shown that colonoscopy is much more effective in reducing the incidence and mortality of distal colorectal cancer.

Complications were analyzed in five studies, with the following results: piercing, 0.01 % (95 % CI 0.006 to 0.02) and bleeding, 0.05 % (95 % CI: 0.02 to 0.09). No studies evaluating the effectiveness of virtual colonoscopy in reducing colorectal cancer mortality (13, 24, 40) were found.

#### **3.4. Sigmoidoscopy and colonoscopy**

The Colombian guide (18) indicates that screening with flexible sigmoidoscopy and colono‐ scopy can reduce mortality, and both strategies – sigmoidoscopy and colonoscopy – would fare as diagnostic tools. The European GPC appoints only sigmoidoscopy as the strategy to reduce the incidence and mortality when this strategy is part of an organized screening program.

#### **3.5. Computed tomography colonography (virtual colonoscopy) versus colonoscopy**

Pickhardt and colleagues (37) evaluated the sensitivity of CTC and colonoscopy for the detection of colorectal cancer. The research group indicates that although most studies argue that the test performance can be improved in line with the prevalence of the disease, the sensitivity of CTC remained independent of the prevalence. The evaluation of the quality design of this study was low in all outcomes, through the use of a single database and in relation to the population, including only two studies of the average-risk population and age higher than 50 years; in addition, the evidence is indirect. The evidence presented by the Blue Cross and Blue Shield Association (39) was rated low because it only included two studies of individuals at average risk and a description of their results does not show confidence intervals. The study of El-Maraghi (40) lacks clear criteria for inclusion and description of homogeneity tests, key in systematic reviews.

#### **3.6. Capsule endoscopy versus colonoscopy**

The objective of the study from the Medical Advisory Secretariat (41) was to determine the effectiveness and safety of capsule endoscopy in identifying colorectal cancer and adenoma‐ tous polyps in the average-risk population greater than 50 years old and as a screening strategy. They conclude that although capsule endoscopy is a noninvasive method and has lower sensitivity and specificity and accuracy than colonoscopy, its ability in detecting colorectal cancer has not been studied. The qualifying result of the outcomes of sensitivity, specificity, detection of polyps greater than or equal to 6 mm, and detection of any polyp independent of size was low due to the lack of reporting of homogeneity tests.

#### **3.7. Screening intervals**

cancer mortality in 22–31 %; in meta-analysis, the pooled risk reduction for incidence was estimated to be 18 % (CI 95 % 11–25%) and for mortality from colorectal cancer 28 % (CI 95 % 20–35 %). The result of observational studies for distal colorectal cancer was strong in reduced incidence and mortality, reduction of 64 % (CI 95 % 50–74 %) in incidence colorectal rates and 66 % (38–81 %) in reduced mortality rates for cancer (6). In this study, it was shown that colonoscopy is much more effective in reducing the incidence and mortality of distal colorectal

Complications were analyzed in five studies, with the following results: piercing, 0.01 % (95 % CI 0.006 to 0.02) and bleeding, 0.05 % (95 % CI: 0.02 to 0.09). No studies evaluating the effectiveness of virtual colonoscopy in reducing colorectal cancer mortality (13, 24, 40) were

The Colombian guide (18) indicates that screening with flexible sigmoidoscopy and colono‐ scopy can reduce mortality, and both strategies – sigmoidoscopy and colonoscopy – would fare as diagnostic tools. The European GPC appoints only sigmoidoscopy as the strategy to reduce the incidence and mortality when this strategy is part of an organized screening

**3.5. Computed tomography colonography (virtual colonoscopy) versus colonoscopy**

Pickhardt and colleagues (37) evaluated the sensitivity of CTC and colonoscopy for the detection of colorectal cancer. The research group indicates that although most studies argue that the test performance can be improved in line with the prevalence of the disease, the sensitivity of CTC remained independent of the prevalence. The evaluation of the quality design of this study was low in all outcomes, through the use of a single database and in relation to the population, including only two studies of the average-risk population and age higher than 50 years; in addition, the evidence is indirect. The evidence presented by the Blue Cross and Blue Shield Association (39) was rated low because it only included two studies of individuals at average risk and a description of their results does not show confidence intervals. The study of El-Maraghi (40) lacks clear criteria for inclusion and description of

The objective of the study from the Medical Advisory Secretariat (41) was to determine the effectiveness and safety of capsule endoscopy in identifying colorectal cancer and adenoma‐ tous polyps in the average-risk population greater than 50 years old and as a screening strategy. They conclude that although capsule endoscopy is a noninvasive method and has lower sensitivity and specificity and accuracy than colonoscopy, its ability in detecting colorectal cancer has not been studied. The qualifying result of the outcomes of sensitivity, specificity, detection of polyps greater than or equal to 6 mm, and detection of any polyp independent of

cancer.

found.

program.

**3.4. Sigmoidoscopy and colonoscopy**

8 Screening for Colorectal Cancer with Colonoscopy

homogeneity tests, key in systematic reviews.

**3.6. Capsule endoscopy versus colonoscopy**

size was low due to the lack of reporting of homogeneity tests.

The European guide (16) indicates that in the case of choosing colonoscopy because of the prevalence, there is a case for screening individuals under age 50 or adults over 75 years or more, due to comorbidities that may outweigh the benefits of the examination. The American guide (42) supported this age of completion of screening; it believes that screening can be studied in the age range of 76–84 years and recommends its accomplishment in individuals 85 years or older.

#### **4. Discussion**

For colonoscopy screening test, the meta-analysis of Niv et al. (38), performed with cohort studies, suggests that colonoscopy is a possible and desirable CRC screening method in asymptomatic individuals; however, it is not clearly described how the critical evaluation of the articles was performed nor how the reference to the possible publication bias is made. Colonoscopy no randomized controlled trials that indicate the incidence and mortality from colorectal cancer. Evidence from observational studies suggests that this test could reduce the incidence and mortality from colorectal cancer, according to the National Polyp Study (43, 44) and the Italian multicenter study (45), and although it is a highly sensitive technique (26), the evidence is insufficient to exclude or include colonoscopy as the first-line screening strategy (17,25,41). As an additional point, colonoscopy requires specific training by the clinician, is more expensive than other screening tests, presents greater risk of complications during the test, and increases the likelihood of injury in cases in which polypectomy is performed.

Virtual colonoscopy is a highly specific test, particularly for polyps <9mm; however, the sensitivity varies widely, even for large polyps. The low efficiency of studies to explain the variability of the sensitivity requires rethinking and further study of this test, before recom‐ mending it for everyday use in the assessment of polyps (46).

Sigmoidoscopy, colonoscopy, barium enema, and even virtual colonoscopy are up-to-date diagnostic tools for which a greater number of studies evaluating the effectiveness of these methods as the primary screening tests in asymptomatic persons are required (13, 24, 42).

There is a possible overrepresentation of the state of health of the people attending for colonoscopy in analytical observational studies, which may incur information bias. Further‐ more, it is possible confounding by these context variables that influence the development of a colonoscopy as well as the incidence of CRC, such as family history, diet, and physical activity.

#### **5. Conclusion**

We conclude that colonoscopy may be offered as a CRC screening tool for the high-risk population as well as the asymptomatic population since the diagnostic yield for polyps and cancer is high. These results have to be evaluated with further research and weighed against the cost, accessibility, quality of life of patients, and possible serious complications.

### **Author details**

Carlos Eduardo Pinzon-Florez1\*, Oscar Andres Gamboa-Garay1,2 and Diana Marcela Diaz-Quijano1

\*Address all correspondence to: carlos.pinzon1@unisabana.edu.co

1 Health Research Group. Universidad de La Sabana, Colombia

2 Analyses Research Group. National Cancer Institute. Bogota, Colombia

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2 Analyses Research Group. National Cancer Institute. Bogota, Colombia

1 Health Research Group. Universidad de La Sabana, Colombia

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## **Screening and Surveillance Colonoscopy**

Rotimi R. Ayoola, Hamza Abdulla, Evan K. Brady, Muhammed Sherid and Humberto Sifuentes

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/61204

#### **Abstract**

Colorectal cancer is a major cause of worldwide morbidity and mortality. As such, there are many guidelines and recommendations set forth by various medical societ‐ ies regarding colonoscopy for screening and surveillance. The universal goal of these guidelines is to reduce colorectal cancer prevalence and mortality. Recommendations for colorectal cancer screening and surveillance using colonoscopy vary slightly be‐ tween medical society guidelines and are often dictated by some combination of age, known disease severity, length of time since last study, family history, and comorbid conditions.

**Keywords:** Screening, surveillance, colonoscopy, recommendations, colorectal cancer

#### **1. Introduction**

Colorectal cancer is the second leading cause of death from cancer in the United States, as well as the fourth most common cause of cancer-related death, and the third most diagnosed cancer worldwide.[1, 3] In 2008, there were an estimated 1.2 million newly diagnosed cases of colorectal cancer worldwide and an estimated 609,000 colorectal cancer-related deaths.[3] In 2014, it was estimated that there were 136,830 newly diagnosed cases of colorectal cancer and nearly 50,310 deaths associated with this disease in the Unites States alone.[4] The age-adjusted incidence of colorectal cancer in the United States was 43.7 cases per 100,000 population among men and women based on reported cases from 2007 to 2011.[4] In 2011, there were an estimated 1,162,426 people living with colon and rectum cancer in the United States.[4] Screening of those at average risk may result in lower mortality rates by detecting cancers at earlier and more curable stages. Also, detection of cancer-precursor lesions may reduce the incidence of colorectal cancer if removed on endoscopic screening tests.[5, 6] The incidence and mortality

© 2015 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

of colorectal cancer have declined from 2002 to 2010 in the United States,[7] possibly due to improvement in the adherence to screening and surveillance guidelines.

#### **2. Colorectal cancer screening**

#### **2.1. Prevention strategies**

Recommended strategies for colorectal cancer screening can be divided into two categories: stool tests (occult blood and DNA tests) and structural examinations (flexible sigmoidoscopy, colonoscopy, double contrast barium enema, capsule endoscopy, and computed tomographic colonography). Each screening method has its own advantages and disadvantages, which are summarized in Table 1. Screening is currently recommended beginning at 50 years of age in average-risk populations, and varies in populations with increased risks.[6, 8]


**Table 1.** Advantages and disadvantages of screening tests

Strategies used to identify patients at an increased risk for developing colorectal cancer should be started early. Before determining the best screening tool, clinicians should determine a patient's level of risk. The most common indicator of increased risk is a first-degree relative with colorectal cancer. Diagnosis of colorectal cancer in a first-degree relative before 50 years of age is concerning for hereditary gastrointestinal cancer syndromes such as Lynch syndrome, familial adenomatous polyposis (FAP), attenuated familial adenomatous polyposis (AFAP), and MUTYH-associated polyposis (MAP). Patients with hereditary gastrointestinal cancer syndromes require a special timing for endoscopic screening and surveillance. Colonoscopy is the preferred screening test in these persons, which should be initiated at 40 years of age or 10 years younger than the age at which the family member was diagnosed with colorectal cancer, whichever comes first.[6, 8] Patients with chronic ulcerative colitis or colitis due to Crohn's disease are at increased risk for colorectal cancer and should undergo a screening colonoscopy after 8-10 years.[6, 8] Prior colorectal cancer or polyps also increases the risk of colorectal cancer, especially if polyps are large, or have villous architecture.[12]

#### **2.2. Identifying high-risk individuals**

of colorectal cancer have declined from 2002 to 2010 in the United States,[7] possibly due to

Recommended strategies for colorectal cancer screening can be divided into two categories: stool tests (occult blood and DNA tests) and structural examinations (flexible sigmoidoscopy, colonoscopy, double contrast barium enema, capsule endoscopy, and computed tomographic colonography). Each screening method has its own advantages and disadvantages, which are summarized in Table 1. Screening is currently recommended beginning at 50 years of age in

Inexpensive, easily done at home Low sensitivity, annually repeated,

lack of compliance

intervals

occult, annually repeated, unknown adherence, low sensitivity for advanced adenomas

Expensive, sensitivity and specificity unknown, uncertain screening

Not been proven to reduce incidence or

Proximal colon cancer may be missed

Bowel preparation and expertise needed, expensive, invasive with

possible complications

mortality, bowel prep needed, unknown management of polyps <6 mm in diameter, radiation exposure

improvement in the adherence to screening and surveillance guidelines.

average-risk populations, and varies in populations with increased risks.[6, 8]

easily done at home

diameter; not invasive

of the distal colon

60% reduction in mortality from cancer

diameter, 53-72% reduction in incidence and 31% reduction in mortality from colorectal cancer, lesions can be detected and removed

during one examination

**Fecal immunochemical test** Inexpensive, easily done at home More expensive than guaiac fecal

**Test Advantages Disadvantages**

**Stool DNA** More accurate than blood detection;

**CT Colonography** High sensitivity of lesions >10 mm in

**Sigmoidoscopy** Can be done in office without sedation,

**Colonoscopy** 90% sensitivity for lesions >10 mm in

\*\*Data from Lieberman[6], Baxter, et al.[9], Muller, et al.[10], and Singh, et al.[11]

**Table 1.** Advantages and disadvantages of screening tests

**2. Colorectal cancer screening**

16 Screening for Colorectal Cancer with Colonoscopy

**2.1. Prevention strategies**

**Sensitive guaiac fecal occult**

**blood test**

The risk of developing colorectal cancer is largely multifactorial. The factors associated with an increased risk of colorectal cancer include lack of physical activity, obesity, high-fat and low-fiber diets, tobacco use, gender, ethnicity, and genetics. There is limited evidence to suggest that lifestyle modification alone in adults will reduce the risk of this cancer.[6, 13] Aspirin, nonsteroidal anti-inflammatory drugs, and hormone-replacement therapy can decrease the risk of adenomas or colorectal cancer but are not recommended in prevention of colorectal cancer because the possible adverse effects are higher than the potential benefits.[6, 14, 15]

#### **2.3. Screening modalities**

Multiple tests are used as options for colorectal cancer screening. Stool-based tests can improve disease prognosis by detecting early cancers. Endoscopic or radiologic tests can visualize the bowel mucosa and detect polyps that can be removed before malignant transformation. Sensitivities of various screening modalities (Table 2) and screening guidelines (Table 3) can be very useful when choosing the most appropriate screening test.



\*Advanced adenoma is defined as tubular adenoma that is ≥10 mm in diameter or with villous histologic features or highgrade dysplasia.

**Table 2.** Sensitivity of one-time colorectal cancer screening tests



\* Data from Lieberman[6], Preventive Services Task Force[14], Levin et al.[21], Preventive Services Task Force[14], and Whitlock et al.[22]; ACS-MSTF-ACR denotes American cancer Society, US Multisociety task force on Colorectal Cancer, and American College of Radiology; and USPSTF denotes US Preventive services Task Force.

**Table 3.** US colorectal cancer screening guidelines, 2008\*

#### *2.3.1. Fecal screening tests*

**Test Sensitivity References**

Allison et al.[15], Levin et al.[21], Whitlock et al. [22], Ahlquist et al.[20]

> Levin et al.[21], Whitlock et al.[22]

Allison et al.[15], Itzkowitz et al.[23]

Lieberman[6], Shelby et al.[25]

Lieberman[6], Imperiale et al.[19], Schoenfeld et al.[26], Lieberman et al.[27], Pickhardt et al.[28], Cotton et al.[29], Rockey et al.[30]

**Recommended Interval for**

**Rescreening**

Uncertain

Recommended 1 yr

sensitivity test only 1 yr

Recommended; high-

Not Recommended (insufficient evidence to assess sensitivity and specificity of fecal DNA)

50-75% 20-25%

60-85% 20-50%

≥80% 40%

\*Advanced adenoma is defined as tubular adenoma that is ≥10 mm in diameter or with villous histologic features or high-

90% (if ≥10 mm

70%

probably >90%

colon)

51% 18% Imperiale et al.[19]

diameter) Johnson et al.[24]

**Sensitive guaiac fecal occult blood**

18 Screening for Colorectal Cancer with Colonoscopy

**Immunochemical fecal occult blood**

**CT Colonography** Uncertain;

**Sigmoidoscopy** >95% (for distal

**Colonoscopy** >95% 88-98%

**Table 2.** Sensitivity of one-time colorectal cancer screening tests

**Screening Test ACS-MSTF-ACR USPSTF**

cancer

cancer

cancer

Recommended if "/>50% sensitivity for colorectal

Recommended if >50% sensitivity for colorectal

Recommended if >50% sensitivity for colorectal

**(three stool samples)**

**(one-three stool samples)**

**Old stool DNA test (one stool sample)**

**New stool DNA test (one stool sample)**

grade dysplasia.

**blood test**

**Stool DNA test**

**Sensitive guaiac fecal occult**

**Fecal immunochemical test**

**test**

**test**

Fecal screening tests use small stool samples to help determine the presence of colorectal cancer. Fecal screening tests include Guaiac-based fecal occult blood test, immunochemicalbased fecal occult blood test, also known as fecal immunochemical test (FIT), and Cologuard (fecal DNA testing, combined with hemoglobin and DNA methylation assays). These tests are easily performed at home or in a clinical office, are noninvasive, inexpensive, without direct adverse health effects, and require few specialized resources. One disadvantage of fecal testing is that positive results require colonoscopy evaluation to confirm or exclude the diagnosis of colorectal cancer.

Guaiac fecal occult blood tests detect hemoglobin peroxidase activity and turn guaiacimpregnated paper blue, but are not specific for human blood. Three separate stool samples per test are preferred for better sensitivity.[21] The fecal occult blood test is associated with significant false-positive results, which may lead to unnecessary follow-up colonoscopies. In the Minnesota trial, false-positive test results were found in almost 9% of fecal occult blood testing.[3] The cost-effectiveness of colorectal cancer screening with an annual or biennial fecal occult blood test varied from US\$ 5,691 to US\$ 17,805 per life-year gained.[31] Randomized, controlled trials in which standard guaiac tests were administered annually or biennially have shown that cancers are detected at an earlier and more curable stage when compared with no regular screening. Over a period of 10-13 years, regular guaiac screening tests result in a reduction of colorectal cancer mortality by 15-33%.[6, 8, 32]

FIT uses antibodies specific to hemoglobin to screen for colorectal cancer. It is more accurate than the guaiac test.[33, 37] As a result, FIT is now recommended as the first-choice fecal occult blood test in colorectal cancer screening.[38] FIT has sensitivity for detecting cancer of 60-85% with the use of one to three stool samples.[4, 6, 22] Cologuard is a screening modality that tests stool DNA for specific mutations that are associated with colorectal cancer. These specific segments of cellular DNA are excreted in stool and can be detected with the use of polymerase chain reaction (PCR) amplification. Newer versions of the test are currently being developed; however, overall performance, utility, and cost-effectiveness has not been well studied.

#### *2.3.2. Structural examinations of the colon*

Colorectal cancers can be detected through physical exams with a digital rectal examination, but there is little evidence to support the effectiveness of digital rectal exam in the detection of colorectal cancer and, therefore, it is not recommended in the current screening guidelines (Table 3).

Anatomical examination of the colon is effective in detection of early cancer and precancerous lesions. Radiography imaging such as barium enema and computed tomographic (CT) colonography can be used to detect lesions. In clinical studies of CT colonography for polyp detection with expert radiologists, 90% of polyps 10 mm or larger in diameter were identified correctly, with a false-positive rate of 14%.[6] CT colonography is not as sensitive for polyps less than 6 mm. There are currently no conclusive studies supporting appropriate screening intervals for negative results or suitable next steps for polyps less than 6 mm. While radiation exposure during CT colonography is considered minimal, the cumulative radiation exposure puts people at increased risk for developing other types of radiation-related cancers. Addi‐ tionally, cost-effectiveness of CT colonography has not been thoroughly studied in comparison to other modalities.

Before colonoscopy became available, barium enema was the primary means of detecting polyps, and their removal required surgical colostomy.[39] Barium enema examination is not the best test for identifying precancerous lesions and is rarely used for colorectal-cancer screening in current practice.[6] Double-contrast barium enema is another screening modality that involves the patient drinking contrast, which coats the intestinal mucosa with barium. Then, the colon is insufflated with air and multiple radiographs are taken under fluoroscopy. Double-contrast barium enema detects about half of adenomas larger than 1 cm and 39% of all polyps.[40] Retrospective studies have found that double-contrast barium enema failed to diagnose 15-22% of colorectal cancers.[41] If an abnormality is found, then colonoscopy evaluation should follow. False-positives or inconclusive results can be a result of stool, mucosal irregularities, or air. Barium enemas are safe and typically do not require sedation, but may cause the patient discomfort during the procedure. The usage rates of double contrast barium enema for colorectal cancer screening recently declined with improved screening tools, but may be useful where colonoscopy is not readily available.[42]

Endoscopic screening is more sensitive than fecal testing for the detection of adenomatous polyps.[37, 43, 45] In the United Kingdom, one-time screening with flexible sigmoidoscopy significantly reduced the incidence of colorectal cancer by 23% and cancer-related mortality by 31%.[45, 46] Studies, with the use of screening colonoscopy, have shown that more than 30% of patients with advanced neoplasia have proximal lesions that would not be identified with sigmoidoscopy alone.[47, 48]

The most performed indication for colonoscopy in the United States is for screening and surveillance purposes. Colonoscopy can detect a wide range of colon pathologies including polyps, angiodysplasias, hemorrhoids, and cancer. Colonoscopy also permits therapeutic interventions. The procedure is highly feasible and relatively safe. The quality of the procedure depends on an adequate bowel preparation. The patient is typically sedated throughout the procedure. Colonoscopy can reduce the incidence and the mortality of colorectal cancer.[9, 27, 49] Endoscopic procedures may be uncomfortable for patients and carry the risks of perfora‐ tion and bleeding, especially when polypectomy is performed. The risk of serious adverse events is 3-5 events per 1000 colonoscopies.[6]

Capsule endoscopy has the potential to become a useful screening tool. A camera, in the size and shape of a pill, is swallowed to help visualize the gastrointestinal tract. Reductions of incidence and mortality have not yet been studied using this modality. Capsule endoscopy does not require sedation or radiation. However, accuracy data show inferior screening performance compared to colonoscopy.[3] Despite all these available methods, colorectal cancer screening rates are still suboptimal. In a National Health Interview Survey in 2010, the rate of screening was only 58.6%.[39]

#### **2.4. Screening guidelines**

with the use of one to three stool samples.[4, 6, 22] Cologuard is a screening modality that tests stool DNA for specific mutations that are associated with colorectal cancer. These specific segments of cellular DNA are excreted in stool and can be detected with the use of polymerase chain reaction (PCR) amplification. Newer versions of the test are currently being developed; however, overall performance, utility, and cost-effectiveness has not been well studied.

Colorectal cancers can be detected through physical exams with a digital rectal examination, but there is little evidence to support the effectiveness of digital rectal exam in the detection of colorectal cancer and, therefore, it is not recommended in the current screening guidelines

Anatomical examination of the colon is effective in detection of early cancer and precancerous lesions. Radiography imaging such as barium enema and computed tomographic (CT) colonography can be used to detect lesions. In clinical studies of CT colonography for polyp detection with expert radiologists, 90% of polyps 10 mm or larger in diameter were identified correctly, with a false-positive rate of 14%.[6] CT colonography is not as sensitive for polyps less than 6 mm. There are currently no conclusive studies supporting appropriate screening intervals for negative results or suitable next steps for polyps less than 6 mm. While radiation exposure during CT colonography is considered minimal, the cumulative radiation exposure puts people at increased risk for developing other types of radiation-related cancers. Addi‐ tionally, cost-effectiveness of CT colonography has not been thoroughly studied in comparison

Before colonoscopy became available, barium enema was the primary means of detecting polyps, and their removal required surgical colostomy.[39] Barium enema examination is not the best test for identifying precancerous lesions and is rarely used for colorectal-cancer screening in current practice.[6] Double-contrast barium enema is another screening modality that involves the patient drinking contrast, which coats the intestinal mucosa with barium. Then, the colon is insufflated with air and multiple radiographs are taken under fluoroscopy. Double-contrast barium enema detects about half of adenomas larger than 1 cm and 39% of all polyps.[40] Retrospective studies have found that double-contrast barium enema failed to diagnose 15-22% of colorectal cancers.[41] If an abnormality is found, then colonoscopy evaluation should follow. False-positives or inconclusive results can be a result of stool, mucosal irregularities, or air. Barium enemas are safe and typically do not require sedation, but may cause the patient discomfort during the procedure. The usage rates of double contrast barium enema for colorectal cancer screening recently declined with improved screening tools,

Endoscopic screening is more sensitive than fecal testing for the detection of adenomatous polyps.[37, 43, 45] In the United Kingdom, one-time screening with flexible sigmoidoscopy significantly reduced the incidence of colorectal cancer by 23% and cancer-related mortality by 31%.[45, 46] Studies, with the use of screening colonoscopy, have shown that more than 30% of patients with advanced neoplasia have proximal lesions that would not be identified

but may be useful where colonoscopy is not readily available.[42]

with sigmoidoscopy alone.[47, 48]

*2.3.2. Structural examinations of the colon*

20 Screening for Colorectal Cancer with Colonoscopy

(Table 3).

to other modalities.

Two major guidelines, from the US Preventive Services Task Force (USPSTF) and a joint guideline from the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology (ACS-MSTF), were released in 2008 regarding colorectal cancer screening in the United States (Table 3). The joint guidelines recommend structural examinations for cancer prevention. The ACS-MSTF recommends offering screening beginning at age 50 years for average-risk patients, and continued surveillance every 10 years, if negative. In average-risk patients, CT colonography should be performed every 5 years, flexible sigmoidoscopy every 5 years, and double-contrast barium enema every 5 years. The joint guidelines recommend fecal occult blood testing with sensitive guaiac method or fecal immunochemical-based test every year for screening. Screening should be terminated if a patient's life expectancy is less than 10 years.[21] Prior to screening, patients should under‐ stand that a positive test indicates a need for colonoscopy. There are no specific guidelines regarding colorectal cancer screening for sex or ethnicity but the American College of Gastro‐ enterology supports initiation of screening in African Americans at 45 years of age.[8]

The US Preventive Services Task Force does not recommend CT colonography or stool DNA testing. The USPSTF recommends three screening options for adults 50-75 years old: sensitive fecal occult blood testing annually, flexible sigmoidoscopy every 5 years with sensitive fecal occult blood test every 3 years, and colonoscopy every 10 years. Screening for patients older than 75 is not routinely recommended by the USPSTF, and recommends against screening over the age of 85 years.[14] Colorectal cancer screening in older patients who have never undergone formal screening is controversial and there are currently no guidelines regarding appropriate screening in these scenarios. The risk of colorectal cancer and advanced polyps continues to increase in age even after 75 years. Thus, the decision to screen between the ages of 75 and 85 years should be discussed with and individualized to each patient depending on health status and other comorbidities.

In Europe, fecal occult blood testing is implemented at higher rates than in the United States. The fecal occult blood test for individuals aged 50-74 years at average-risk has been recom‐ mended to date by the European Union guidelines for colorectal screening, annually or biennially.[15]

The British Society of Gastroenterology (BSG) and the Association of Coloproctology for Great Britain and Ireland (ACPGBI) aimed to provide guidance on the appropriateness, method, and frequency of screening for people at moderate- and high-risk for colorectal cancer.[50]

### **3. Colorectal cancer surveillance**

Surveillance colonoscopy refers to colonoscopy examination performed in asymptomatic individuals with previously identified cancerous or precancerous lesions. Colonoscopy surveillance is used to identify any recurrent or new neoplasia in these individuals.[51] High adenoma detection rate on follow-up colonoscopy (30-50%) provides the rationale for surveil‐ lance colonoscopy.[52, 56] There is strong evidence that surveillance colonoscopy decreases colorectal cancer incidence and colorectal cancer-related mortality.[57]

The timing of subsequent surveillance is crucial. Studies demonstrate both the protective effect and cost-effectiveness of performing surveillance colonoscopy on high-risk populations.[58] The overall impact of surveillance is not well defined and may be decreased by an inappro‐ priate utilization of resources and nonadherence to published guidelines.[59]

#### **3.1. Recommendations for surveillance colonoscopy**

Guidelines from Gastrointestinal societies in the United States, the United Kingdom, and the European Union follow a risk stratification policy to time their surveillance intervals.

The US Multisociety Task Force (US MSTF) guidelines were published in 2008 and categorize patients into two major risk groups based on the likelihood of development of advanced neoplasia (Table 4). In 2012, the US MSFT updated their guidelines to address the role of serrated polyps, risk of interval colorectal cancer, and proximal colorectal cancer (Table 5).

The European Society of Gastrointestinal Endoscopy (ESGE) updated their guidelines in 2013 and formulated a risk stratification and surveillance strategy similar to the United States (Table 4 and Table 5). A new recommendation was to increase the interval from 3 years to 5 years after a normal follow-up colonoscopy in the high-risk group (3-4 adenomas, villous features or high-grade dysplasia, or ≥10 mm in size).

The UK guidelines are based on adenoma size and number without incorporating histological findings. It stratifies patients into low-, moderate-, and high-risks groups. It also recommends a "single clearing examination" at 1 year for high-risk patients (≥5 small adenomas or ≥3 adenomas, at least 1 of which is ≥1 cm).


**Table 4.** Risk stratification criteria

years should be discussed with and individualized to each patient depending on health status

In Europe, fecal occult blood testing is implemented at higher rates than in the United States. The fecal occult blood test for individuals aged 50-74 years at average-risk has been recom‐ mended to date by the European Union guidelines for colorectal screening, annually or

The British Society of Gastroenterology (BSG) and the Association of Coloproctology for Great Britain and Ireland (ACPGBI) aimed to provide guidance on the appropriateness, method, and frequency of screening for people at moderate- and high-risk for colorectal cancer.[50]

Surveillance colonoscopy refers to colonoscopy examination performed in asymptomatic individuals with previously identified cancerous or precancerous lesions. Colonoscopy surveillance is used to identify any recurrent or new neoplasia in these individuals.[51] High adenoma detection rate on follow-up colonoscopy (30-50%) provides the rationale for surveil‐ lance colonoscopy.[52, 56] There is strong evidence that surveillance colonoscopy decreases

The timing of subsequent surveillance is crucial. Studies demonstrate both the protective effect and cost-effectiveness of performing surveillance colonoscopy on high-risk populations.[58] The overall impact of surveillance is not well defined and may be decreased by an inappro‐

Guidelines from Gastrointestinal societies in the United States, the United Kingdom, and the

The US Multisociety Task Force (US MSTF) guidelines were published in 2008 and categorize patients into two major risk groups based on the likelihood of development of advanced neoplasia (Table 4). In 2012, the US MSFT updated their guidelines to address the role of serrated polyps, risk of interval colorectal cancer, and proximal colorectal cancer (Table 5). The European Society of Gastrointestinal Endoscopy (ESGE) updated their guidelines in 2013 and formulated a risk stratification and surveillance strategy similar to the United States (Table 4 and Table 5). A new recommendation was to increase the interval from 3 years to 5 years after a normal follow-up colonoscopy in the high-risk group (3-4 adenomas, villous features

The UK guidelines are based on adenoma size and number without incorporating histological findings. It stratifies patients into low-, moderate-, and high-risks groups. It also recommends a "single clearing examination" at 1 year for high-risk patients (≥5 small adenomas or ≥3

European Union follow a risk stratification policy to time their surveillance intervals.

colorectal cancer incidence and colorectal cancer-related mortality.[57]

**3.1. Recommendations for surveillance colonoscopy**

or high-grade dysplasia, or ≥10 mm in size).

adenomas, at least 1 of which is ≥1 cm).

priate utilization of resources and nonadherence to published guidelines.[59]

and other comorbidities.

22 Screening for Colorectal Cancer with Colonoscopy

**3. Colorectal cancer surveillance**

biennially.[15]


**Table 5.** Surveillance interval recommendation

A recently published study, which analyzed 3226 post-polypectomy patients, compared the US MSTF guidelines with the British Society of Gastroenterology (BSG) guidelines. The study showed that the application of the UK guidelines into the US population reclassified 26.3% of patients from high-risk to a higher-risk category and 7% to a lower-risk category.[60] The study also showed a net 19% of patients benefiting from detection 2 years earlier without substan‐ tially increasing rates of colonoscopy.[60]

#### **3.2. Sessile serrated adenomas/polyps and surveillance colonoscopy**

Sessile serrated adenoma/polyp (SSA/P) is a term used to describe polyps or adenomas characterized by the presence of a sawtooth appearance to crypt contour with prominent dilatation, serrations, and lateralization at the crypt base.[51] The discovery of the serrated adenoma/polyp pathway and the development of colorectal cancer has led to increased interest and focus on the understanding of the histological and molecular changes that lead to CRC. Hypermethylation of genes in serrated lesions leads to microsatellite instability and rapid development of colorectal cancer.[61]

Endoscopically, serrated lesions have a similar appearance to hyperplastic polyps and are often misdiagnosed as such. A recent study showed that as high as one-third of recently diagnosed hyperplastic polyps ≥5 mm were reclassified into SSA/P after a second pathology review.[62] The CARE study found that serrated lesions were five times more likely to be incompletely resected by polypectomy compared to conventional adenomas.[63] Serrated polyps larger than 1 cm or with a dysplastic component are considered advanced polyps.[63]

Surveillance recommendations for serrated adenomas/polyps are inconsistent among re‐ searchers and gastrointestinal societies and long-term studies evaluating SSA/P are limited. US MSTF and ESGE classifies serrated polyps <10 mm with no dysplasia as low-risk and serrated polyps ≥10 mm or those with dysplasia as high-risk. Both societies recommend surveillance colonoscopy in 3 years in high-risk. For low-risk lesions, ESGE recommends 10 year follow-up, whereas US MSTF recommends 5-year follow-up.[14, 50, 64]

#### **3.3. Serrated polyposis syndrome**

The World Health Organization defines serrated polyposis syndrome by either the presence of five or more serrated polyps proximal to the sigmoid colon (at least two of which must be ≥10 mm) or 20 or more serrated polyps of any size distributed throughout the colon.[65] US MSFT and ESGE recommend one-year follow-up surveillance in this patient population. [14, 66] ESGE also recommends referral for genetic counseling.[14, 66]

#### **3.4. Effect of positive family history on surveillance intervals**

Patients with a family history of colorectal carcinoma are at higher risk of developing highrisk adenoma and colorectal carcinoma. US MSTF recommends shortening the surveillance interval from 10 years to 5 years in patients with low-risk findings on colonoscopy and a firstdegree relative with colorectal cancer prior to the age of 60.[14] US MSTF also recommends surveillance with colonoscopy as the preferred method.[14]

#### **3.5. Surveillance colonoscopy in the elderly**

There is a significant increase in incidence of both CRC and adenomas with increasing age.[14] The age at which screening colonoscopy should be performed remains controversial. Studies that examined the role of age in surveillance colonoscopy found no association with increasing age and polyp recurrence and concluded it was not necessary to tailor surveillance guidelines by age.[5, 67, 70] Retrospective studies have also shown that comorbidities reduce the benefits of CRC screening. The US MSTF does not give a specific age at which screening can be ceased, but recommends that competing comorbidities and life expectancy should be considered before ordering cancer screening at any age.[14]

#### **3.6. Surveillance colonoscopy and physician nonadherence to guidelines**

Nonadherence to guidelines remains a major problem in healthcare policy. The overuse of resources could lead to increased demand for colonoscopy, shifting resources from screening, and thus decreasing the cost-effectiveness of CRC screening program by increasing the unnecessary costs and possibility of adverse events. Alternatively, underuse of colonoscopy in surveillance may lead to suboptimal prevention of colorectal cancer. Schohen, et al. retrospectively evaluated 3,627 screening patients with a history of adenoma removal and found overuse of endoscopy in low-risk patients and underuse in high-risk patients.[71] The reasons for guideline nonadherence include lack of strong evidence to support the surveillance intervals, having multiple guidelines with inconsistent recommendations, lack of awareness of current evidence, fear of legal implication, suboptimal bowel preparation, financial incen‐ tive for performing the procedure, and miscommunication between gastroenterologist and primary care providers.[72] Measures to improve adherence to guidelines include continued medical education; written recommendations by endoscopist regarding the follow-up interval after the pathology report; quality improvement interventions such as reminder devices; improvement of bowel preparation quality; automated electronic alerting system[72, 73]; and continuous quality improvement process for colonoscopy (education, monitoring, audits, and financial incentives/penalties).[74]

#### **4. Conclusion**

and focus on the understanding of the histological and molecular changes that lead to CRC. Hypermethylation of genes in serrated lesions leads to microsatellite instability and rapid

Endoscopically, serrated lesions have a similar appearance to hyperplastic polyps and are often misdiagnosed as such. A recent study showed that as high as one-third of recently diagnosed hyperplastic polyps ≥5 mm were reclassified into SSA/P after a second pathology review.[62] The CARE study found that serrated lesions were five times more likely to be incompletely resected by polypectomy compared to conventional adenomas.[63] Serrated polyps larger than

Surveillance recommendations for serrated adenomas/polyps are inconsistent among re‐ searchers and gastrointestinal societies and long-term studies evaluating SSA/P are limited. US MSTF and ESGE classifies serrated polyps <10 mm with no dysplasia as low-risk and serrated polyps ≥10 mm or those with dysplasia as high-risk. Both societies recommend surveillance colonoscopy in 3 years in high-risk. For low-risk lesions, ESGE recommends 10-

The World Health Organization defines serrated polyposis syndrome by either the presence of five or more serrated polyps proximal to the sigmoid colon (at least two of which must be ≥10 mm) or 20 or more serrated polyps of any size distributed throughout the colon.[65] US MSFT and ESGE recommend one-year follow-up surveillance in this patient population. [14,

Patients with a family history of colorectal carcinoma are at higher risk of developing highrisk adenoma and colorectal carcinoma. US MSTF recommends shortening the surveillance interval from 10 years to 5 years in patients with low-risk findings on colonoscopy and a firstdegree relative with colorectal cancer prior to the age of 60.[14] US MSTF also recommends

There is a significant increase in incidence of both CRC and adenomas with increasing age.[14] The age at which screening colonoscopy should be performed remains controversial. Studies that examined the role of age in surveillance colonoscopy found no association with increasing age and polyp recurrence and concluded it was not necessary to tailor surveillance guidelines by age.[5, 67, 70] Retrospective studies have also shown that comorbidities reduce the benefits of CRC screening. The US MSTF does not give a specific age at which screening can be ceased, but recommends that competing comorbidities and life expectancy should be considered

1 cm or with a dysplastic component are considered advanced polyps.[63]

year follow-up, whereas US MSTF recommends 5-year follow-up.[14, 50, 64]

66] ESGE also recommends referral for genetic counseling.[14, 66]

**3.4. Effect of positive family history on surveillance intervals**

surveillance with colonoscopy as the preferred method.[14]

**3.5. Surveillance colonoscopy in the elderly**

before ordering cancer screening at any age.[14]

development of colorectal cancer.[61]

24 Screening for Colorectal Cancer with Colonoscopy

**3.3. Serrated polyposis syndrome**

Colorectal cancer screening and surveillance have been shown to provide many benefits. The associated risks are relatively minor and vary greatly on the particular screening test, and surveillance regimen. Patients should be informed that screening and surveillance reduce the risk of colorectal cancer, but may require additional tests and/or procedures to diagnose and manage the pathologic findings. Colorectal cancer screening rate is still suboptimal in the United States and this rate could be improved by dedicated patients and clinician reminders, patients' education, outreach, and follow-up. Screening and surveillance must be targeted to appropriate patients and occur at recommended intervals to ensure proper prevention.

#### **Author details**

Rotimi R. Ayoola\* , Hamza Abdulla, Evan K. Brady, Muhammed Sherid and Humberto Sifuentes\*

\*Address all correspondence to: rayoola@gru.edu

Georgia Regents University, Augusta, GA, USA

#### **References**


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26 Screening for Colorectal Cancer with Colonoscopy

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## **Indications and Outcomes**

## **Colonoscopy — Indications and Contraindications**

Jigar Bhagatwala, Arpit Singhal, Summer Aldrugh, Muhammed Sherid, Humberto Sifuentes and Subbaramiah Sridhar

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/61097

#### **Abstract**

This chapter discusses some of the major indications and contraindications for colonoscopy. Advances in colonoscopic techniques have expanded the role of colonoscopy beyond conventional screening, surveillance, and diagnosis to various complex therapeutic and interventional utilities. Several guidelines with new information are being published and updated regularly in the field of colonoscopy and are currently used in clinical practice. However, there is still a lack of welldesigned randomized clinical trials investigating the role of colonoscopy in early diagnosis and treatment of various conditions and its impact on long-term survival and disease status. Nevertheless, retrospective observational studies and a few randomized clinical trials abundantly supply data supporting the role of colonoscopy in the diagnosis and management of colonic pathologies in the absence of comparable alternatives.

**Keywords:** Colonoscopy, Indication, Contraindication, Screening, Surveillance, Di‐ agnostic, Therapeutic

#### **1. Introduction**

In the 1960s, Drs. William Wolff and Hiromi Shinya developed a way to probe the full length of the colon using a tube with electronic sensors [1]. Since its inception, colonoscopy has

© 2015 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

become a very popular method for screening of colorectal cancers and for treating a variety of conditions of the lower gastrointestinal tract. The decision to perform colonoscopy should take into account the indication and contraindication for the procedure, the risks of the procedure, and the cost. A key quality measure of colonoscopy is the indication for the procedure, because as high as 20-50% of colonoscopies are performed for inappropriate indications [2]. Performing colonoscopy for inappropriate indications not only exposes patients to procedure-related complications such as bowel perforation, bleeding, infection, and cardiovascular events, but also increases on the health-care-related cost. Therefore, several societies including the American Society of Gastrointestinal Endoscopy (ASGE) and the European Panel on the Appropriateness of Gastrointestinal Endoscopy (EPAGE), have established guidelines for appropriate use of colonoscopy. In this chapter, we aim to outline the common indications and contraindications for performing colonoscopy and detail the evidence supporting the facts.

#### **2. Indications for colonoscopy (table 1)**

#### **2.1. Lower gastrointestinal (GI) bleeding**

Lower GI bleeding may occur in the form of occult bleeding, melena, scant intermittent hematochezia, or severe hematochezia [3]. Lower GI bleeding from any cause requires colonoscopy either urgently or routinely. Patients with occult GI bleeding require colonoscopy to exclude malignant or adenomatous etiologies. Patients who are not good candidates for colonoscopy can be evaluated using CT colonography [4]. In patients presenting with melena, upper GI endoscopy is performed first to identify any upper GI causes. If the upper GI endoscopy does not reveal a source of bleeding, colonoscopy is then indicated to identify any colonic source. Intermittent scant hematochezia can be diagnosed by anoscopy with/without sigmoidoscopy for low-lying lesions in the anus, rectum, and sigmoid in patients who are younger than 40. However, colonoscopy may still be required if a definitive source cannot be identified. On the other hand, colonoscopy is the recommended procedure for patients with intermittent hematochezia who have one of the following risk factors: age >50, family history of colon cancer, or other alarming symptoms such as weight loss, anemia, and change in bowel habits [5, 6]. Overall, colonoscopy has been reported to have a higher yield than other modal‐ ities such as proctosigmoidoscopy, single-contrast barium studies, or combined flexible sigmoidoscopy and double-contrast barium enema for diagnosis of lower GI bleeding. In case of severe hematochezia, hemodynamic stability determines the diagnostic and therapeutic approach [7-9]. In hemodynamically stable patients, urgent (within 8-24 h) colonoscopy is recommended [10-13]. In critically ill patients, upper endoscopy is indicated first followed by colonoscopy after excluding the upper GI tract as the source of bleeding [14]. The therapeutic indications of colonoscopy for the treatment of lower GI bleeding are discussed separately in this chapter.


#### **2.2. Screening and surveillance of colorectal polyps and cancers**

#### *2.2.1. Colon cancer*

become a very popular method for screening of colorectal cancers and for treating a variety of conditions of the lower gastrointestinal tract. The decision to perform colonoscopy should take into account the indication and contraindication for the procedure, the risks of the procedure, and the cost. A key quality measure of colonoscopy is the indication for the procedure, because as high as 20-50% of colonoscopies are performed for inappropriate indications [2]. Performing colonoscopy for inappropriate indications not only exposes patients to procedure-related complications such as bowel perforation, bleeding, infection, and cardiovascular events, but also increases on the health-care-related cost. Therefore, several societies including the American Society of Gastrointestinal Endoscopy (ASGE) and the European Panel on the Appropriateness of Gastrointestinal Endoscopy (EPAGE), have established guidelines for appropriate use of colonoscopy. In this chapter, we aim to outline the common indications and contraindications for performing colonoscopy and detail the evidence supporting the facts.

Lower GI bleeding may occur in the form of occult bleeding, melena, scant intermittent hematochezia, or severe hematochezia [3]. Lower GI bleeding from any cause requires colonoscopy either urgently or routinely. Patients with occult GI bleeding require colonoscopy to exclude malignant or adenomatous etiologies. Patients who are not good candidates for colonoscopy can be evaluated using CT colonography [4]. In patients presenting with melena, upper GI endoscopy is performed first to identify any upper GI causes. If the upper GI endoscopy does not reveal a source of bleeding, colonoscopy is then indicated to identify any colonic source. Intermittent scant hematochezia can be diagnosed by anoscopy with/without sigmoidoscopy for low-lying lesions in the anus, rectum, and sigmoid in patients who are younger than 40. However, colonoscopy may still be required if a definitive source cannot be identified. On the other hand, colonoscopy is the recommended procedure for patients with intermittent hematochezia who have one of the following risk factors: age >50, family history of colon cancer, or other alarming symptoms such as weight loss, anemia, and change in bowel habits [5, 6]. Overall, colonoscopy has been reported to have a higher yield than other modal‐ ities such as proctosigmoidoscopy, single-contrast barium studies, or combined flexible sigmoidoscopy and double-contrast barium enema for diagnosis of lower GI bleeding. In case of severe hematochezia, hemodynamic stability determines the diagnostic and therapeutic approach [7-9]. In hemodynamically stable patients, urgent (within 8-24 h) colonoscopy is recommended [10-13]. In critically ill patients, upper endoscopy is indicated first followed by colonoscopy after excluding the upper GI tract as the source of bleeding [14]. The therapeutic indications of colonoscopy for the treatment of lower GI bleeding are discussed separately in

**2. Indications for colonoscopy (table 1)**

**2.1. Lower gastrointestinal (GI) bleeding**

36 Screening for Colorectal Cancer with Colonoscopy

this chapter.

According to the World Health Organization report in 2012, colorectal cancer (CRC) is the third most common cancer in men (746,000 cases, 10% of the total) and the second in women (614,000 cases, 9.2% of the total) worldwide. In 2014, the American Cancer Society predicted that about 136,830 people would be diagnosed with colorectal cancer in the United States, and about 50,310 people were predicted to die of the disease. Recent studies show declining in the CRC incidence and mortality rates, which have been attributed to the awareness of the risk factors and reduced exposure to them, the effect of early detection and prevention through polypec‐ tomy, and improved treatment [15]. The recommendations for screening colonoscopies are divided based on the known risk factor profile: 1) screening in the average-risk population and 2) screening in patients with a family history of colon cancer.

In the average-risk patient, current American, European, and Asian guidelines recommend beginning CRC screening with colonoscopy at the age of 50 years and every 10 years thereafter regardless of the gender. However, the American College of Gastroenterology recommends that the screening colonoscopy begin at the age of 45 years in African Americans [16, 17]. Published evidence favoring the effectiveness of colonoscopy in reducing mortality from CRC by routine colonoscopy is insufficient because of a lack of randomized controlled trials and the limited consensus in guidelines on the appropriateness of colonoscopy. However, a few studies have modeled and predicted the impact of screening colonoscopy on CRC incidence and mortality using various transition models in hypothetical average-risk individuals aged 50 years. These studies have found that initial screening colonoscopy and repeat colonoscopy every 10 years might reduce CRC incidence by 58% and the reduction in CRC mortality is approximately 64% [18, 19]. In the average-risk individuals, yearly fecal occult blood testing (FOBT) and flexible sigmoidoscopy (FSIG) every 3 years are also accepted methods of screening for CRC. A follow-up colonoscopy, however, is warranted to completely visualize the entire length of the colon for patients with positive FOBT results or FSIG findings of adenoma in the distal colon [20-23].

Family history of CRC is a major risk factor for CRC. It has been estimated that the first-degree relatives of CRC patients have two- to threefold increased risk of dying from CRC, and the risk is inversely associated with the age of diagnosis of the affected family member [24]. Patients with a single first-degree relative with CRC or advanced adenoma (adenoma ≥1 cm in size, with high-grade dysplasia, or villous elements) diagnosed at age ≥60 years are recommended to undergo routine CRC screening same as an average-risk individual begin‐ ning at age 50 years. On the other hand, patients with a single first-degree relative with CRC or advanced adenoma diagnosed at age <60 years, or two first-degree relatives with CRC or advanced adenomas should receive colonoscopy every 5 years beginning at age 40, or 10 years earlier than the age at diagnosis of the youngest affected relative, whichever comes first [16]. The data supporting these recommendations emerge from the retrospective studies rather than the randomized control trials [25, 26].

Patients with a family history of hereditary nonpolyposis colorectal cancer (HNPCC), an autosomal dominant disease, are recommended to start the CRC screening at the age of 20-25 years or 10 years prior to the earliest age of HNPCC diagnosis in the patient's family member, whichever comes first. The recommended interval for colonoscopy is every 1-2 years until age 40, then annually thereafter [27-30]. This condition, in particular, has two-thirds of adenomas occurring on the right side and warrants colonoscopy for complete colonic surveillance [31]. Indications for performing colonoscopy in individuals with a history of familial adenomatous polyposis (FAP) are guideline-dependent after genetic testing returns positive. FSIG and colonoscopy have not been compared head-to-head regarding their effectiveness and reducing mortality in patients with FAP in the clinical trials and, as such, either FSIG or colonoscopy annually is recommended, starting at the age of 10-12 years [16]. A colonoscopy is deemed necessary when polyps are detected on FSIG and a decision to perform polypectomy is made.

#### *2.2.2. Surveillance after polypectomy*

Post-polypectomy surveillance constitutes 20% of the performed colonoscopies, thereby constituting a large share in the amount of health care expenditure [32, 33]. Adhering to the indications for the repeat colonoscopy for the surveillance of CRC after the first colonoscopy, therefore, is very important as earlier colonoscopy can increase the risks to the patient and add to the health care cost whereas delaying the surveillance can also increase the risks by increasing the chances of missed interval cancers. Various observational studies report a 2-5% risk of an advanced neoplasia 5-10 years after a negative colonoscopy, a risk that is comparable to the risk of advanced colonic neoplasia in the average-risk patients undergoing their first colonoscopy [34-39]. Moreover, the risk of developing CRC 10 years after a negative colono‐ scopy is reported to be significantly lower (adjusted OR 0.26) [36, 40], supporting the current recommendation of repeat colonoscopy every 10 years in the average-risk general population.

Although the detection and removal of polyp(s) can offer a significant reduction in the mortality of CRC, the development of interval cancers, i.e., the cancers occurring after the initial colonoscopy with polypectomy, appears to be the highest in the first 3-5 years. In 2012, the United States Multi-Society Task Force (USMSTF) published a revision of the 2006 guidelines on post-polypectomy surveillance and divided recommendations based on the presence of polyp(s) (hyperplastic vs. adenomatous), the number and the size of adenomatous polyp(s), villous component and high-grade dysplasia in the polyp, and the presence of serrated lesions or serrated polyposis syndrome (>20 serrated polyps of any size throughout the colon) at baseline colonoscopy. In 2013, the European Society of Gastrointestinal Endoscopy (ESGE) published its post-polypectomy surveillance guidelines, stratifying risk into: low risk (1-2 adenomas <1 cm), intermediate risk (3-4 small adenomas or one >1 cm), and high risk (>5 small adenomas or >3 adenomas with at least one >1 cm) based on the first colonoscopy. According to the USMSTF guideline, it is indicated that patients with 1-2 tubular adenomas <1 cm have a repeat colonoscopy in 10 years; whereas patients with a high-risk adenoma (defined as adenoma with villous histology, high-grade dysplasia, adenoma>10 mm, or three or more adenomas) are recommended to have surveillance interval of 3 years. According to the ESGE guideline, the high-risk group should undergo surveillance at 1 year, the intermediate-risk group at 3-yearly intervals until two consecutive examinations are negative, and the low-risk group requires no surveillance colonoscopy or 5-yearly colonoscopy until one negative examination after which surveillance can be discontinued. The evidence supporting the indications in the arena of surveillance for the serrated polyp is insufficient. According to the USMSTF guideline, sessile serrated polyp(s) <1 cm with no dysplasia should be considered low risk and can be followed at a 5-year interval. However, sessile serrated polyp(s) ≥1 cm or sessile serrated polyp with dysplasia or serrated adenoma should undergo surveillance at 3 years and serrated polyposis syndrome should be surveyed annually. The ESGE recommends that patients with serrated polyps <10 mm in size without dysplasia should be classified as low risk, whereas patients with large serrated polyps (≥10 mm) or those with dysplasia as high risk and undergo surveillance accordingly. Patients with ≥5 serrated polyps proximal to the sigmoid, of which ≥2 are sized ≥10mm, or with ≥20 serrated polyps of any size are classified as serrated polyposis and should be referred for genetic testing.

#### *2.2.3. CRC post-resection surveillance*

the limited consensus in guidelines on the appropriateness of colonoscopy. However, a few studies have modeled and predicted the impact of screening colonoscopy on CRC incidence and mortality using various transition models in hypothetical average-risk individuals aged 50 years. These studies have found that initial screening colonoscopy and repeat colonoscopy every 10 years might reduce CRC incidence by 58% and the reduction in CRC mortality is approximately 64% [18, 19]. In the average-risk individuals, yearly fecal occult blood testing (FOBT) and flexible sigmoidoscopy (FSIG) every 3 years are also accepted methods of screening for CRC. A follow-up colonoscopy, however, is warranted to completely visualize the entire length of the colon for patients with positive FOBT results or FSIG findings of

Family history of CRC is a major risk factor for CRC. It has been estimated that the first-degree relatives of CRC patients have two- to threefold increased risk of dying from CRC, and the risk is inversely associated with the age of diagnosis of the affected family member [24]. Patients with a single first-degree relative with CRC or advanced adenoma (adenoma ≥1 cm in size, with high-grade dysplasia, or villous elements) diagnosed at age ≥60 years are recommended to undergo routine CRC screening same as an average-risk individual begin‐ ning at age 50 years. On the other hand, patients with a single first-degree relative with CRC or advanced adenoma diagnosed at age <60 years, or two first-degree relatives with CRC or advanced adenomas should receive colonoscopy every 5 years beginning at age 40, or 10 years earlier than the age at diagnosis of the youngest affected relative, whichever comes first [16]. The data supporting these recommendations emerge from the retrospective studies rather than

Patients with a family history of hereditary nonpolyposis colorectal cancer (HNPCC), an autosomal dominant disease, are recommended to start the CRC screening at the age of 20-25 years or 10 years prior to the earliest age of HNPCC diagnosis in the patient's family member, whichever comes first. The recommended interval for colonoscopy is every 1-2 years until age 40, then annually thereafter [27-30]. This condition, in particular, has two-thirds of adenomas occurring on the right side and warrants colonoscopy for complete colonic surveillance [31]. Indications for performing colonoscopy in individuals with a history of familial adenomatous polyposis (FAP) are guideline-dependent after genetic testing returns positive. FSIG and colonoscopy have not been compared head-to-head regarding their effectiveness and reducing mortality in patients with FAP in the clinical trials and, as such, either FSIG or colonoscopy annually is recommended, starting at the age of 10-12 years [16]. A colonoscopy is deemed necessary when polyps are detected on FSIG and a decision to perform polypectomy is made.

Post-polypectomy surveillance constitutes 20% of the performed colonoscopies, thereby constituting a large share in the amount of health care expenditure [32, 33]. Adhering to the indications for the repeat colonoscopy for the surveillance of CRC after the first colonoscopy, therefore, is very important as earlier colonoscopy can increase the risks to the patient and add to the health care cost whereas delaying the surveillance can also increase the risks by increasing the chances of missed interval cancers. Various observational studies report a 2-5%

adenoma in the distal colon [20-23].

38 Screening for Colorectal Cancer with Colonoscopy

the randomized control trials [25, 26].

*2.2.2. Surveillance after polypectomy*

There are no clear survival benefits for performing colonoscopy in patients who have had colon cancer resection. However, a majority of the groups and societies such as American Cancer Society (ACS), and a joint American Cancer Society/US Multi-Society Task Force on Colorectal Cancer, Cancer Care Ontario [41-44], recommend post CRC resection surveillance. An indication to perform colonoscopy in these patients will help detect metachronous CRCs and polyps as well as anastomotic recurrences of the initial primary cancer at a stage that would allow further treatment. Currently, a follow-up colonoscopy is indicated at 1 year after the surgical removal of CRC. If no new cancer or polyp(s) is identified, a colonoscopy is repeated at 3 years and at 5 years if the findings are negative for interval development of cancer. An exception to this indication is HNPCC, which requires colonoscopic surveillance every 1-2 years regardless of the surgical resection of the cancer.

#### *2.2.4. Inflammatory bowel diseases and other colitis*

The indications for colonoscopy in inflammatory bowel disease (IBD), namely ulcerative colitis (UC) and Crohn's disease (CD) fall under a large spectrum. Colonoscopic diagnosis and differentiation between the UC and CD, assessment of the extent and severity of disease activity, treatment effectiveness, surveillance of malignancies, and endoscopic treatment, such as stricture dilation, are all within the scope of colonoscopy and its indications in IBD. Currently, American, European, and other international societies and guideline-defining bodies recommend endoscopic visualization of the entire colon for the initial diagnosis of IBD and other colitis [45-48]. The clinical presentation and laboratory data characterizing both diseases may overlap but endoscopic visualization of the mucosa of the rectum, colon, and terminal ileum, and the extent of the disease involvement may help differentiate the disease processes. Moreover, colonoscopy offers the opportunity to perform biopsy, which is the major advantage of colonoscopy. Unless contraindicated because of severe colitis or possible toxic megacolon, a full colonoscopy with intubation of the terminal ileum should be performed during the initial evaluation of patients with a clinical presentation suggestive of IBD. Ileoscopy is superior for the diagnosis of CD of the terminal ileum when compared with radiological methods, especially for mild lesions [49, 50]. During the colonoscopic examina‐ tion, biopsy samples should be obtained both from areas affected by the disease and from unaffected areas. After initiating therapy, a smaller number of biopsy samples may be necessary to confirm the diagnosis. In postsurgical follow-up, biopsies of the neoterminal ileum are indicated when disease recurrence is suspected. In patients who have undergone ileal pouch-anal anastomosis, biopsies of the afferent limb are indicated when Crohn's disease is suspected [46]. Other forms of colitis, such as drug-induced, infectious, vascular, and radiation colitis also present in a similar pattern and require colonoscopy at baseline for the diagnosis and the assessment of severity.

Patients with IBD have an increased risk of CRC compared to those without IBD [51-55]. In fact, CRC accounts for one-sixth of ulcerative colitis-related deaths [56]. There is a lack of randomized control studies demonstrating the effectiveness of colonoscopy in improving survival in the IBD patients from CRC. However, numerous observational studies have reported that colonoscopic surveillance of CRC in IBD offers early detection of cancers and improves CRC-related survival in IBD patients [57, 58]. In a retrospective study of 6,823 patients with IBD in US tertiary referral hospitals followed-up for at least 3 years, the incidence of CRC among patients without a recent colonoscopy was 2.7% which was significantly higher than among patients with a recent colonoscopy (1.6%) [59]. Additionally, a colonoscopy within 6-36 months before diagnosis was associated with a 64% reduction in mortality rate [59]. According to most guidelines, colonoscopies are indicated for CRC screening starting at 8-10 years from initiation of IBD-related symptoms [48, 53, 60-62]. The National Institute for Health and Clinical Excellence (NICE) London 2011 guideline, however, recommends only offering colonoscopic surveillance to patients with Crohn's colitis involving more than 1 segment of the colon or left-sided or more extensive UC, but not isolated ulcerative proctitis. Most guidelines recommend yearly follow-up colonoscopy for high-risk patients (those with primary sclerosing cholangitis, extensive colitis, active endoscopic or histologic inflammation, a family history of CRC in a first-degree relative before 50 years of age, personal history of dysplasia, presence of strictures on colonoscopy, and, possibly, gender), and every 2-5 years for those without major risk factors.

#### **2.3. Acute and chronic diarrhea**

polyps as well as anastomotic recurrences of the initial primary cancer at a stage that would allow further treatment. Currently, a follow-up colonoscopy is indicated at 1 year after the surgical removal of CRC. If no new cancer or polyp(s) is identified, a colonoscopy is repeated at 3 years and at 5 years if the findings are negative for interval development of cancer. An exception to this indication is HNPCC, which requires colonoscopic surveillance every 1-2

The indications for colonoscopy in inflammatory bowel disease (IBD), namely ulcerative colitis (UC) and Crohn's disease (CD) fall under a large spectrum. Colonoscopic diagnosis and differentiation between the UC and CD, assessment of the extent and severity of disease activity, treatment effectiveness, surveillance of malignancies, and endoscopic treatment, such as stricture dilation, are all within the scope of colonoscopy and its indications in IBD. Currently, American, European, and other international societies and guideline-defining bodies recommend endoscopic visualization of the entire colon for the initial diagnosis of IBD and other colitis [45-48]. The clinical presentation and laboratory data characterizing both diseases may overlap but endoscopic visualization of the mucosa of the rectum, colon, and terminal ileum, and the extent of the disease involvement may help differentiate the disease processes. Moreover, colonoscopy offers the opportunity to perform biopsy, which is the major advantage of colonoscopy. Unless contraindicated because of severe colitis or possible toxic megacolon, a full colonoscopy with intubation of the terminal ileum should be performed during the initial evaluation of patients with a clinical presentation suggestive of IBD. Ileoscopy is superior for the diagnosis of CD of the terminal ileum when compared with radiological methods, especially for mild lesions [49, 50]. During the colonoscopic examina‐ tion, biopsy samples should be obtained both from areas affected by the disease and from unaffected areas. After initiating therapy, a smaller number of biopsy samples may be necessary to confirm the diagnosis. In postsurgical follow-up, biopsies of the neoterminal ileum are indicated when disease recurrence is suspected. In patients who have undergone ileal pouch-anal anastomosis, biopsies of the afferent limb are indicated when Crohn's disease is suspected [46]. Other forms of colitis, such as drug-induced, infectious, vascular, and radiation colitis also present in a similar pattern and require colonoscopy at baseline for the

Patients with IBD have an increased risk of CRC compared to those without IBD [51-55]. In fact, CRC accounts for one-sixth of ulcerative colitis-related deaths [56]. There is a lack of randomized control studies demonstrating the effectiveness of colonoscopy in improving survival in the IBD patients from CRC. However, numerous observational studies have reported that colonoscopic surveillance of CRC in IBD offers early detection of cancers and improves CRC-related survival in IBD patients [57, 58]. In a retrospective study of 6,823 patients with IBD in US tertiary referral hospitals followed-up for at least 3 years, the incidence of CRC among patients without a recent colonoscopy was 2.7% which was significantly higher than among patients with a recent colonoscopy (1.6%) [59]. Additionally, a colonoscopy within 6-36 months before diagnosis was associated with a 64% reduction in mortality rate [59].

years regardless of the surgical resection of the cancer.

*2.2.4. Inflammatory bowel diseases and other colitis*

40 Screening for Colorectal Cancer with Colonoscopy

diagnosis and the assessment of severity.

Patients presenting with acute diarrhea should undergo initial evaluation with stool studies. If blood and stool cultures are inconclusive, or if symptoms persist or worsen despite empiric therapy, then colonoscopy is indicated due to its high diagnostic yield [63]. For most patients with chronic diarrhea, patients with suspected acute diffuse *Clostridium Difficile* colitis, pregnant patients, patients with predominantly left-sided symptoms (tenesmus/urgency) and patients with multiple morbidities, a flexible sigmoidoscopy can be used for the initial evaluation. Even if patients have macroscopically normal-appearing mucosa, biopsies must be obtained to exclude microscopic diseases. If flexible sigmoidoscopy yields inconclusive results, if diarrhea persists, or if there is suspicion of inflammatory bowel disease (IBD) or cancer, then colonoscopy should be the next investigative study.

Histology is an integral component of colonoscopic evaluation of chronic diarrhea because several diseases, such as microscopic colitis, eosinophilic colitis, amyloidosis, and IBD, may appear normal on endoscopy but are abnormal on microscopy. In patients undergoing colonoscopy for chronic diarrhea, IBD or colitis is the most likely disease to be detected [64]. Microscopic colitis can be lymphocytic or collagenous and is characterized by nonbloody, watery diarrhea. On endoscopy, microscopic colitis can be missed because of patchy colonic involvement. Even if mucosa appears normal endoscopically, multiple biopsies from both sides of the colon are necessary to avoid missing microscopic colitis [65]. If there is suspicion of inflammatory diarrhea, then a biopsy of the terminal ileum is helpful in the diagnosis. However, a biopsy of the terminal ileum has the highest diagnostic yield in patients with known or suspected Crohn's disease, terminal ileal abnormalities on imaging, or endoscopic findings of ulcers, ileitis, or erosions [66].

Colonoscopy is not routinely used to evaluate acute diarrhea because it is commonly due to infectious etiology. If stool tests are negative and/or if diarrhea persists, then endoscopy is indicated. An additional important exception is the case of an immunocompromised patient. In a patient with diarrhea with HIV, organ or bone marrow transplant, or on immunosup‐ pressive medications, a colonoscopy with biopsy is necessary to exclude CMV colitis and graft versus host disease (GVHD). In such cases, colonoscopic evaluation of diarrhea has higher sensitivity and cost-effectiveness than FSIG [67]. Patients who undergo stem cell transplant often present with diarrhea in the initial 3 months following transplantation. In these patients, abnormal mucosa on endoscopy has not been shown to correlate with biopsy results. There‐ fore, biopsies of normal and abnormal-appearing mucosa are indicated, especially of the distal colon, which has the highest diagnostic yield in patients undergoing endoscopy for gastroin‐ testinal symptoms [68]. Based on the location of highest diagnostic yield, a flexible sigmoido‐ scopy with distal colon biopsy is indicated in patients with diarrhea suspected of acute GVHD. However, some centers endorse combined upper GI endoscopy as well as colonoscopy in patients following hematopoietic stem cell transplantation to diagnose disease more quickly.

#### **2.4. Therapeutic indications for colonoscopy**

#### *2.4.1. Excision and ablation of lesions*

Endoscopic mucosal resection (EMR) is a method for treating early CRC. Most adenomas and intramucosal cancers can be removed by EMR. For tumors larger than 2 cm, EMR is less likely to achieve complete resection (histopathologically tumor-free lateral and vertical margins of the resected specimens) [69, 70]. Another method, known as endoscopic submucosal dissection (ESD) is also performed in several countries. The procedure is simpler than the laparoscopic colectomy but is time-consuming and carries a higher risk of perforation than EMR. ESD is indicated in lesions >2 cm, lesions that are suspected to be invasive submucosal cancer, and mucosal lesions with fibrosis or local residual early cancer after endoscopic resection. The rate of complete resection for large colorectal tumors by ESD has been reported to be 80-98.9% [71-74]. However, both procedures are operator-dependent and have limited data supporting their use.

#### *2.4.2. Treatment of lower GI bleeding*

Treatment of acute lower GI bleeding from any sources described earlier is indicated either urgently or as an elective procedure. In case of urgent colonoscopy, the colon is prepared using polyethylene glycol based solution administered orally or via nasogastric tube. Currently, metallic clip placement, thermal coagulation, and epinephrine injection are the available methods. Depending on the lesion and the severity of bleeding, colonoscopic intervention with any one of these methods is indicated as the first step in achieving hemostasis. In case of persistent diverticular bleeding, a bleeding vessel can be treated with metallic clip placement [75, 76]. Vascular ectasias can be treated with either thermal or epinephrine injection, though thermal cauterization has 87% of success rate [77]. Cases where a definite bleeding site cannot be located or cases where the visualization of the bleeding source is poor due to inadequate views due to bleeding need referral for angiographic or surgical treatment.

#### *2.4.3. Colonic decompression*

Acute colonic obstruction is a common presentation of colon cancer and, often, the presenting patient is in poor overall health making surgical intervention a suboptimal choice. Since 1990, the utility of colonoscopic interventions via either self-expanding metal stent (SEMS), place‐ ment of a decompression tube, or tumor debulking has become very popular and has been studied more frequently in recent years in various populations. Endoscopic interventions serve as a bridge to surgery or as a palliative measure in patients who are poor surgical candidates. A majority of the studies comparing SEMS placement with surgery has reported high clinical success rates (92%), better symptomatic relief, lower complication rates (<5%), cost-effective‐ ness, and higher patient acceptance and shorter hospital stay with endoscopic SEMS placement [78-83]. Argon plasma coagulation (APC) and snare polypectomy have been used to treat colonic obstruction and maintain luminal patency, and are good alternatives to endoscopic SEMS in treating colonic obstruction [84-86].

Endoscopic decompression of an acute colonic pseudo-obstruction or Ogilvie syndrome is another therapeutic indication for colonoscopy. The etiology of this condition is multifactorial (post-intraabdominal surgery, sepsis, hypothyroidism, neurological disorder, spinal cord injury, etc.) in the absence of a true mechanical obstruction. Bowel ischemia and perforation are dreaded complications and management is often conservative, involving the correction of the underlying disorder. However, in cases where the initial management fails, colonoscopic decompression is indicated [87, 88].

Colonoscopy is also used for decompression of sigmoid and cecal volvulus. Volvulus is a condition in which a part of colon twists upon itself. Due to venous congestion and obstruction to blood flow, tissue viability becomes a major issue. Patients presenting with signs of perforation, peritonitis, bowel necrosis or profound hemodynamic instability need immediate surgery. However, patients with less severe sigmoid and cecal volvulus can be managed endoscopically [89, 90]. Endoscopic correction of sigmoid volvulus achieves better success rates than the correction of cecal volvulus and is associated with a lesser need for surgical intervention [91]. A study by Oren and colleagues reported that sigmoidoscopic correction of sigmoid volvulus with a rectal tube was successful in 78% of patients [92]. Nevertheless, the rate of recurrence of sigmoid volvulus is high, ultimately requiring surgical treatment [93]. Cecal volvulus has been treated endoscopically but due to the high failure rate, often requires surgical intervention for most patients. Surgeons usually combine operative detorsion of cecal volvulus with right hemicolectomy (to prevent recurrence) and either a primary anastomosis or an ileostomy with mucus fistula. In medically unstable, high-risk patients who are poor surgical candidates or have poor vascular supplies to the cecum, cecal volvulus detorsion may be achieved with a cecostomy and cecopexy, which also are associated with significant morbidity and mortality [94]. Colonic volvuluses in other areas such as flexural territories are less common and the indication to perform colonoscopic interventions in these situations is not well studied.

#### *2.4.4. Dilation of colonic stenosis*

abnormal mucosa on endoscopy has not been shown to correlate with biopsy results. There‐ fore, biopsies of normal and abnormal-appearing mucosa are indicated, especially of the distal colon, which has the highest diagnostic yield in patients undergoing endoscopy for gastroin‐ testinal symptoms [68]. Based on the location of highest diagnostic yield, a flexible sigmoido‐ scopy with distal colon biopsy is indicated in patients with diarrhea suspected of acute GVHD. However, some centers endorse combined upper GI endoscopy as well as colonoscopy in patients following hematopoietic stem cell transplantation to diagnose disease more quickly.

Endoscopic mucosal resection (EMR) is a method for treating early CRC. Most adenomas and intramucosal cancers can be removed by EMR. For tumors larger than 2 cm, EMR is less likely to achieve complete resection (histopathologically tumor-free lateral and vertical margins of the resected specimens) [69, 70]. Another method, known as endoscopic submucosal dissection (ESD) is also performed in several countries. The procedure is simpler than the laparoscopic colectomy but is time-consuming and carries a higher risk of perforation than EMR. ESD is indicated in lesions >2 cm, lesions that are suspected to be invasive submucosal cancer, and mucosal lesions with fibrosis or local residual early cancer after endoscopic resection. The rate of complete resection for large colorectal tumors by ESD has been reported to be 80-98.9% [71-74]. However, both procedures are operator-dependent and have limited data supporting

Treatment of acute lower GI bleeding from any sources described earlier is indicated either urgently or as an elective procedure. In case of urgent colonoscopy, the colon is prepared using polyethylene glycol based solution administered orally or via nasogastric tube. Currently, metallic clip placement, thermal coagulation, and epinephrine injection are the available methods. Depending on the lesion and the severity of bleeding, colonoscopic intervention with any one of these methods is indicated as the first step in achieving hemostasis. In case of persistent diverticular bleeding, a bleeding vessel can be treated with metallic clip placement [75, 76]. Vascular ectasias can be treated with either thermal or epinephrine injection, though thermal cauterization has 87% of success rate [77]. Cases where a definite bleeding site cannot be located or cases where the visualization of the bleeding source is poor due to inadequate

Acute colonic obstruction is a common presentation of colon cancer and, often, the presenting patient is in poor overall health making surgical intervention a suboptimal choice. Since 1990, the utility of colonoscopic interventions via either self-expanding metal stent (SEMS), place‐ ment of a decompression tube, or tumor debulking has become very popular and has been studied more frequently in recent years in various populations. Endoscopic interventions serve

views due to bleeding need referral for angiographic or surgical treatment.

**2.4. Therapeutic indications for colonoscopy**

*2.4.1. Excision and ablation of lesions*

42 Screening for Colorectal Cancer with Colonoscopy

*2.4.2. Treatment of lower GI bleeding*

*2.4.3. Colonic decompression*

their use.

Colonoscopic intervention of stenotic lesions such as anastomotic strictures and strictures caused by IBD are among the common indications for performing colonoscopy. Several studies have reported high success rate with a low complications rate. However, recurrence is common. The methods commonly employed for the treatment of colonic stenosis are balloon dilation with or without steroid injection and electro-incision, all of which have been shown to have a variable amount of success [95-101].

#### *2.4.5. Foreign body removal*

The current management of the foreign bodies lying in the lower GI tract is based on the type of foreign body, the proximity to the anus, the injury to the adjacent structure, as well as the surgical and endoscopic expertise at the health care center. A foreign body in the GI tract presents after voluntary or involuntary insertion or ingestion of the foreign body. Very often, the patient tries to manipulate the object and attempts self-exploration to remove it before presenting to the hospital. Endoscopy provides an opportunity to avoid abdominal explora‐ tion. However if the radiological exam or clinical presentation indicates perforation or higherlying object(s), colonoscopy may fail and may pose a delay in surgical management [102-106].

#### **2.5. Miscellaneous indications**

#### *2.5.1. Abnormal radiological examination*

Colonoscopy is commonly performed after an abnormal or suspicious radiological finding in the search for true pathological lesions such as cancers or ulcerative lesions. Filling defect or mucosal defect on barium enema or a luminal narrowing on barium enema or CT scan is routinely evaluated with a colonoscopy. Patients presenting with symptoms suggestive of acute diverticulitis with supportive CT scan findings also need to be evaluated with colono‐ scopy, but only after the acute inflammation has resolved. Air insufflation during colonoscopy in acute diverticulitis can lead to the bowel perforation and is considered a contraindication. A luminal defect or polyp(s) on CT scan or CT colonography is usually followed-up by a colonoscopy when feasible. However, controversy exists between the American College of Radiology, the American Gastroenterology Association, and American College of Gastroen‐ terology regarding the size and number of polyps on CT colonography that meet the require‐ ment for colonoscopy [107-109]. Patients with abnormal positron emission tomography (PET) scan showing a possible colorectal lesion should undergo colonoscopic evaluation. Neverthe‐ less, in the light of insufficient clinical data, the indications for colonoscopy after abnormal radiological exam are based on individual presentation, availability of the endoscopist, age, and other comorbidities of the patient.

#### *2.5.2. Isolated unexplained abdominal pain*

Patients presenting with symptoms of chronic (>3 months) abdominal pain and nonspecific abdominal discomfort might require colonoscopy. In the era of thorough radiologic studies, the need for colonoscopy emerges after noninvasive diagnostic modalities fail and symptoms persist. There is no clear indication for performing colonoscopy in patients presenting with unexplained abdominal pain or discomfort. A detailed history and physical examination provide diagnostic clues but a diagnostic workup often ends up requiring colonoscopy. The diagnostic yield of colonoscopy has been previously studied in retrospective studies. For example, in a study by Neugut et al., a total of 7% of patients who presented with abdominal pain (n=113) either had carcinoma or a polyp >1 cm in size on colonoscopy [110]. It is worth mentioning that detection of the pathological process does not offer symptomatic relief in these cases. In a more recent study by Kueh and colleagues, the diagnostic yield of colonoscopy was evaluated from 2005 to 2010 in a tertiary center in New Zealand among the patients who presented with isolated abdominal pain, which accounted for 1.2% of all colonoscopies (n=2633). The diagnostic yield of colonoscopy for a cancer, adenoma, diverticulosis, or hemorrhoid in the patients with abdominal pain was significantly lower in this cohort than the yield of colonoscopy performed for other symptoms such as rectal bleeding and/or iron deficiency anemia [111].

#### *2.5.3. Chronic constipation*

*2.4.5. Foreign body removal*

44 Screening for Colorectal Cancer with Colonoscopy

**2.5. Miscellaneous indications**

*2.5.1. Abnormal radiological examination*

and other comorbidities of the patient.

*2.5.2. Isolated unexplained abdominal pain*

The current management of the foreign bodies lying in the lower GI tract is based on the type of foreign body, the proximity to the anus, the injury to the adjacent structure, as well as the surgical and endoscopic expertise at the health care center. A foreign body in the GI tract presents after voluntary or involuntary insertion or ingestion of the foreign body. Very often, the patient tries to manipulate the object and attempts self-exploration to remove it before presenting to the hospital. Endoscopy provides an opportunity to avoid abdominal explora‐ tion. However if the radiological exam or clinical presentation indicates perforation or higherlying object(s), colonoscopy may fail and may pose a delay in surgical management [102-106].

Colonoscopy is commonly performed after an abnormal or suspicious radiological finding in the search for true pathological lesions such as cancers or ulcerative lesions. Filling defect or mucosal defect on barium enema or a luminal narrowing on barium enema or CT scan is routinely evaluated with a colonoscopy. Patients presenting with symptoms suggestive of acute diverticulitis with supportive CT scan findings also need to be evaluated with colono‐ scopy, but only after the acute inflammation has resolved. Air insufflation during colonoscopy in acute diverticulitis can lead to the bowel perforation and is considered a contraindication. A luminal defect or polyp(s) on CT scan or CT colonography is usually followed-up by a colonoscopy when feasible. However, controversy exists between the American College of Radiology, the American Gastroenterology Association, and American College of Gastroen‐ terology regarding the size and number of polyps on CT colonography that meet the require‐ ment for colonoscopy [107-109]. Patients with abnormal positron emission tomography (PET) scan showing a possible colorectal lesion should undergo colonoscopic evaluation. Neverthe‐ less, in the light of insufficient clinical data, the indications for colonoscopy after abnormal radiological exam are based on individual presentation, availability of the endoscopist, age,

Patients presenting with symptoms of chronic (>3 months) abdominal pain and nonspecific abdominal discomfort might require colonoscopy. In the era of thorough radiologic studies, the need for colonoscopy emerges after noninvasive diagnostic modalities fail and symptoms persist. There is no clear indication for performing colonoscopy in patients presenting with unexplained abdominal pain or discomfort. A detailed history and physical examination provide diagnostic clues but a diagnostic workup often ends up requiring colonoscopy. The diagnostic yield of colonoscopy has been previously studied in retrospective studies. For example, in a study by Neugut et al., a total of 7% of patients who presented with abdominal pain (n=113) either had carcinoma or a polyp >1 cm in size on colonoscopy [110]. It is worth mentioning that detection of the pathological process does not offer symptomatic relief in these cases. In a more recent study by Kueh and colleagues, the diagnostic yield of colonoscopy was Chronic constipation, as defined by the Rome III criteria [112], is reported to be associated with an increased risk of colon cancer in retrospective studies from the United States [113, 114], Australia [115], and Japan [116]. In contrast, no such association was found in several other studies [117-119]. Interestingly, the yield of colon cancer in colonoscopy performed for constipation alone was lower than in colonoscopy performed for routine colorectal cancer screening [120]. Patients with chronic constipation who present with alarming symptoms such as rectal bleeding, melena, iron-deficiency anemia, unintentional weight loss, or are >50 years should be evaluated with a colonoscopy to identify the etiology of the obstruction, such as cancer, stricture, or extrinsic compression. Colonoscopy can be used to treat chronic consti‐ pation based on the etiology. In patients who have undergone prior abdominal surgery, have inflammatory bowel disease, or are prone to ischemia, colonoscopy is used to dilate fibrotic strictures that lead to constipation [121-123]. Patients suffering from chronic constipation due to neurogenic bowel or acute colonic pseudo-obstruction also benefit from a percutaneous endoscopic colostomy [124]. Importantly, chronic constipation as a procedural indication for colonoscopy is independently associated with poor colon preparation requiring a rigorous amount of laxative(s) or a longer duration of preparation [125, 126].

#### *2.5.4. Preoperative and intraoperative localization of colonic lesions*

Colonic lesions, depending on the size and consistency, may pose some difficulty in localiza‐ tion by surgeons during the surgical procedure, and this could be even more difficult for laparoscopic surgeries than for open procedures. In such cases, localization of a mass or polyp of interest is very important. Preoperative colonoscopy to localize the lesion using penetrating India ink, Spot, or indocyanine green is becoming a common practice [127, 128]. The dye migrates to the peritoneal surface and allows for accurate localization. An alternative colono‐ scopic method of applying clips around the area of interest has also been studied, which requires intraoperative ultrasound to precisely locate the site. Both methods have their own advantages and disadvantages, such as inflammatory reaction to the dye, micro-abscesses, broad spreading of the dye in the field in smaller lesions, migration of the metallic clips, false localization, or inadvertent injection of dye in the adjacent vital structures. A recent review reported that the accuracy of endoscopic tattooing is 70-100% and the incidence of intraoper‐ ative invisible lesions is 1.6-15% [129]. The complications reviewed were mostly related to transmural injection and the spillage rates varied from 2.4 to 13% and were asymptomatic. Intraoperative colonoscopy can also be performed to localize the site of a tumor or a polypec‐ tomy site. However, intraoperative colonoscopy is an understudied field and has reported problems with insufflated air in the colon which interferes with the surgical technique.

#### **3. Contraindications for colonoscopy (table 2)**

A patient who is either unwilling to give informed consent, or has given informed consent but is uncooperative and/or unable to achieve adequate sedation for colonoscopy, should not undergo colonoscopy. Colonoscopy is also contraindicated for known or suspected colonic perforation. Medical conditions associated with a high risk of perforation such as severe toxic megacolon and fulminant colitis are considered contraindications to colonoscopy. Although not strictly contraindicated, severe IBD with deep ulceration in the rectum/distal sigmoid colon and acute diverticulitis increase the risk of colonic perforation. The risk factors for colonic perforation during colonoscopy are age > 65, low body mass index, female gender, hypoalbu‐ minemia, inpatient status, critically ill condition, multiple morbidities, IBD, and other forms of colitis such as ischemic colitis, colonic stricture dilation, polypectomy, foreign body removal, and hemostasis such as cautery [130-132].

Patients who are or are suspected of becoming hemodynamically unstable should be medically stabilized before colonoscopy. In patients who have had a myocardial infarc‐ tion, a colonoscopy performed in the first 3 weeks following the infarction can provoke an arrhythmia although the only reported complications during colonoscopy in the 30 days following an myocardial infarction are hypotension and bradycardia [133]. Adequate bowel preparation is necessary because inadequate or poor bowel preparation increases colonosco‐ py duration with an increase in complications as well as an increase in the number of missed adenomas and high-risk lesions [134].


**Table 2.** Contraindications for colonoscopy

Patients with severe abdominal pain and peritoneal signs may be at risk for possible complete obstruction or gangrenous bowel and should be evaluated by other modalities first. These patients should not undergo colonoscopy due to the risk of bowel perforation from air insufflation of a distended bowel [135]. Colonoscopic decompression of cecal volvulus, though reported, has a high failure rate. Therefore, cecal volvulus should be managed surgically [94]. Failure of endoscopic bowel detorsion, or colonic volvulus with bowel perforation, bowel infarction, or peritonitis are indications for emergent surgery [135].

### **Author details**

tomy site. However, intraoperative colonoscopy is an understudied field and has reported problems with insufflated air in the colon which interferes with the surgical technique.

A patient who is either unwilling to give informed consent, or has given informed consent but is uncooperative and/or unable to achieve adequate sedation for colonoscopy, should not undergo colonoscopy. Colonoscopy is also contraindicated for known or suspected colonic perforation. Medical conditions associated with a high risk of perforation such as severe toxic megacolon and fulminant colitis are considered contraindications to colonoscopy. Although not strictly contraindicated, severe IBD with deep ulceration in the rectum/distal sigmoid colon and acute diverticulitis increase the risk of colonic perforation. The risk factors for colonic perforation during colonoscopy are age > 65, low body mass index, female gender, hypoalbu‐ minemia, inpatient status, critically ill condition, multiple morbidities, IBD, and other forms of colitis such as ischemic colitis, colonic stricture dilation, polypectomy, foreign body removal,

Patients who are or are suspected of becoming hemodynamically unstable should be medically stabilized before colonoscopy. In patients who have had a myocardial infarc‐ tion, a colonoscopy performed in the first 3 weeks following the infarction can provoke an arrhythmia although the only reported complications during colonoscopy in the 30 days following an myocardial infarction are hypotension and bradycardia [133]. Adequate bowel preparation is necessary because inadequate or poor bowel preparation increases colonosco‐ py duration with an increase in complications as well as an increase in the number of

**3. Contraindications for colonoscopy (table 2)**

46 Screening for Colorectal Cancer with Colonoscopy

and hemostasis such as cautery [130-132].

missed adenomas and high-risk lesions [134].

**Contraindications for colonoscopy:**

4. Known or suspected colonic perforation 5. Severe toxic megacolon and fulminant colitis

**Table 2.** Contraindications for colonoscopy

1. Patient refusal

9. Peritonism

2. Uncooperative patients 3. Inadequate sedation

6. Clinically unstable patients 7. Recent myocardial infarction 8. Inadequate bowel preparation Jigar Bhagatwala, Arpit Singhal, Summer Aldrugh, Muhammed Sherid, Humberto Sifuentes and Subbaramiah Sridhar\*

\*Address all correspondence to: jbhagatwala@gru.edu

Georgia Regents University, Augusta, GA, USA

#### **References**


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