**2. Colorectal cancer screening programs**

CRC screening programs are currently underway in most European countries, Canada, specific regions in North and South America, Asia, and Oceania. The most comprehensive screening strategies were based on fecal occult blood testing, and more recently, the fecal immunochemical test (FIT) [3]. While other options for CRC screening are fecal immunochemical test annually, guaiac-based fecal occult

blood test annually, multi-target stool DNA test every three years, colonoscopy every ten years, computed tomography colonography every five years, and flexible sigmoidoscopy every five years [4].

population with average risk. While in a certain country, opportunistic CRC screening is provided at primary healthcare centres, also catering those with average risk. Therefore, most uptakes are due to routine recommendation offered by

Most of the significant CRC guidelines recommend screening of CRC to start at the age of 50 years old. For instance, the US Preventive Task Force recommends screening for CRC to begin at the age of 50 years and continues until age 75 years. The decision to screen for CRC in adults aged 76 to 85 years should be individualized, taking into account the patient's overall health and prior screening history [5]. For examples, according to Malaysian guideline, screening of colorectal carcinoma (CRC) should be offered at the age of 50 years and continues until age 75 years for the average-risk population. Immunochemical fecal occult blood test (iFOBT) is the preferred method to screen for CRC in an average-risk community. If iFOBT is positive, an early colonoscopy is necessary. Whereas, if iFOBT is negative, the

These screening tests are not only effective in the early discovery of malignant

There were several screening tests available for CRC which vary in terms of their performance accuracy, complication rates, screening uptake as well as costs associated with screening. Among several options available are fecal occult blood test (FOBT), flexible sigmoidoscopy (FS), colonoscopy, colon capsule endoscopy

Fecal test is a non-invasive tool for CRC screening in general population. It can detect presence of blood, proteins e.g. enzyme M2-PK and DNA. Fecal occult blood refers to blood in the feces that is not visibly apparent. A fecal occult blood test (FOBT) is designed to identify hidden or small quantities of blood in fecal sample. There are two main types of FOBTs: guaiac-based fecal occult blood test (gFOBT) and immunochemical fecal occult blood test (iFOBT) which is also known as fecal

FOBT has qualitative and quantitative testing methods. In a meta-analysis of fair to high quality evidence, the pooled sensitivity to detect CRC was 74% (95% CI 62-83) for quantitative test methods and 79% (95% CI 61-90) for qualitative test methods [5]. Immunochemical FOBT (iFOBT) and guaiac-based FOBT (gFOBT) are two methods of qualitative FOBT. The sensitivities of iFOBT and gFOBT are 0.67 (95% CI 0.61-0.73) and 0.54 (95% CI 0.48-0.60) respectively. The specificities of iFOBT and gFOBT are comparable at 0.85 (95% CI 0.83-0.87) and 0.80 (95% CI

Overall, screening with FOBT (either iFOBT or gFOBT) has a 16% reduction in the risk of CRC mortality (RR = 0.84, 95% CI 0.78-0.90) as compared to unscreened population [8], while screening with iFOBT can reduce CRC mortality by 22% as

Other fecal test include fecal M2-PK enzyme detection and fecal DNA tests. Fecal M2-PK has a pooled sensitivity and specificity of 79% (95% CI 73 to 83) and 80% (95% CI 73 to 86) respectively [10]. On the other hand, quantitative fecal DNA

tumors, but also serves as a preventive procedure whereby polyps that could potentially become malignant can be found and removed before becoming

attending doctors, despite low.

*DOI: http://dx.doi.org/10.5772/intechopen.94396*

*Public Health: Prevention*

cancerous [2].

**3.1 Fecal test**

immunochemical test (FIT).

0.78-0.82) respectively [7].

**5**

compared to screening with gFOBT [9].

yearly test should be performed (**Figures 1** and **2**) [6].

**3. Colorectal cancer screening modalities**

(CCE), and computed tomographic colonography (CTC).

CRC screening programs are designed for populations according to risk stratification. In general population-based screening, these programs are offered to the

### **Figure 1.**

*Clinical pathway of screening for colorectal carcinoma. Source: Kamil et al. [6].*


**Figure 2.** *Risk categories for family history with CRC. Source: Kamil et al. [6].*

### *Public Health: Prevention DOI: http://dx.doi.org/10.5772/intechopen.94396*

blood test annually, multi-target stool DNA test every three years, colonoscopy every ten years, computed tomography colonography every five years, and flexible

*Clinical pathway of screening for colorectal carcinoma. Source: Kamil et al. [6].*

*Risk categories for family history with CRC. Source: Kamil et al. [6].*

CRC screening programs are designed for populations according to risk stratification. In general population-based screening, these programs are offered to the

sigmoidoscopy every five years [4].

*Colorectal Cancer*

**Figure 1.**

**Figure 2.**

**4**

population with average risk. While in a certain country, opportunistic CRC screening is provided at primary healthcare centres, also catering those with average risk. Therefore, most uptakes are due to routine recommendation offered by attending doctors, despite low.

Most of the significant CRC guidelines recommend screening of CRC to start at the age of 50 years old. For instance, the US Preventive Task Force recommends screening for CRC to begin at the age of 50 years and continues until age 75 years. The decision to screen for CRC in adults aged 76 to 85 years should be individualized, taking into account the patient's overall health and prior screening history [5]. For examples, according to Malaysian guideline, screening of colorectal carcinoma (CRC) should be offered at the age of 50 years and continues until age 75 years for the average-risk population. Immunochemical fecal occult blood test (iFOBT) is the preferred method to screen for CRC in an average-risk community. If iFOBT is positive, an early colonoscopy is necessary. Whereas, if iFOBT is negative, the yearly test should be performed (**Figures 1** and **2**) [6].

These screening tests are not only effective in the early discovery of malignant tumors, but also serves as a preventive procedure whereby polyps that could potentially become malignant can be found and removed before becoming cancerous [2].

### **3. Colorectal cancer screening modalities**

There were several screening tests available for CRC which vary in terms of their performance accuracy, complication rates, screening uptake as well as costs associated with screening. Among several options available are fecal occult blood test (FOBT), flexible sigmoidoscopy (FS), colonoscopy, colon capsule endoscopy (CCE), and computed tomographic colonography (CTC).

### **3.1 Fecal test**

Fecal test is a non-invasive tool for CRC screening in general population. It can detect presence of blood, proteins e.g. enzyme M2-PK and DNA. Fecal occult blood refers to blood in the feces that is not visibly apparent. A fecal occult blood test (FOBT) is designed to identify hidden or small quantities of blood in fecal sample. There are two main types of FOBTs: guaiac-based fecal occult blood test (gFOBT) and immunochemical fecal occult blood test (iFOBT) which is also known as fecal immunochemical test (FIT).

FOBT has qualitative and quantitative testing methods. In a meta-analysis of fair to high quality evidence, the pooled sensitivity to detect CRC was 74% (95% CI 62-83) for quantitative test methods and 79% (95% CI 61-90) for qualitative test methods [5]. Immunochemical FOBT (iFOBT) and guaiac-based FOBT (gFOBT) are two methods of qualitative FOBT. The sensitivities of iFOBT and gFOBT are 0.67 (95% CI 0.61-0.73) and 0.54 (95% CI 0.48-0.60) respectively. The specificities of iFOBT and gFOBT are comparable at 0.85 (95% CI 0.83-0.87) and 0.80 (95% CI 0.78-0.82) respectively [7].

Overall, screening with FOBT (either iFOBT or gFOBT) has a 16% reduction in the risk of CRC mortality (RR = 0.84, 95% CI 0.78-0.90) as compared to unscreened population [8], while screening with iFOBT can reduce CRC mortality by 22% as compared to screening with gFOBT [9].

Other fecal test include fecal M2-PK enzyme detection and fecal DNA tests. Fecal M2-PK has a pooled sensitivity and specificity of 79% (95% CI 73 to 83) and 80% (95% CI 73 to 86) respectively [10]. On the other hand, quantitative fecal DNA test has a higher sensitivity at 92% (95% CI 84 to 97) to detect CRC [5]. These two fecal tests for CRC screening are, however, not widely used locally in screening for general population due to high cost incurred.

values for detection of polyps by CCE seem to be achievable with a 10-mm cutoff

CTC uses multiple thin slice computed tomographic data to construct images of the bowel mucosa in two or three dimensions in detecting polyps. It requires bowel preparation similar to conventional colonoscopy and during the procedure, air or carbon dioxide is introduced into the rectum via a rubber catheter. No sedation is

Estimated sensitivities for patients with polyps or adenomas ≥6 mm were 75.9% (95% CI 62.3–85.8) and 82.9% (95% CI 73.6–89.4), with corresponding specificities 94.6% (95% CI 90.4–97.0) and 91.4% (95% CI 84.1–95.5) respectively. On the other hand, estimated sensitivities for patients with polyps or adenomas ≥10 mm were 83.3% (95% CI 76.8–89.0) and 87.9% (95% CI 82.1–92.0), with corresponding specificities 98.7% (95% CI 97.6–99.3) and 97.6% (95% CI 95.0–98.9) respectively [19]. The major drawbacks of CTC are that it is non-therapeutic, with the need for colonoscopy after the identification of polyps for excision and tissue diagnosis. Other reasons include argument for radiation exposure, presence of flat adenomas that are more likely to be missed by CTC than colonoscopy, and issues of incidental

Participation in screening has varied greatly among different regions. The Netherlands showed the highest participation rate (68.2%) and some areas of Canada showed the lowest (16%). Participation rates were highest among women and in programs that used the iFOBT test. The iFOBT test has been the most widely test used in screening program worldwide nowadays. The advent of this test has increased participation rates and the detection of positive results [13].

In a large scale study conducted in Asia Pacific region, 27% of respondents aged 50 years and older had undergone previous CRC testing; the Philippines (69%), Australia (48%), and Japan (38%) had the highest participation rates, whereas India (1.5%), Malaysia (3%), Indonesia (3%), Pakistan (7.5%), and Brunei (13.7%) had

Community with cancer tends to present to cancer services in the later stages of the disease, and this late presentation has severe, often fatal, consequences. Therefore, increasing awareness about cancer signs and symptoms could contribute to earlier presentation and improvements in cancer outcomes Despite the prevalence of colorectal cancer and the many screening tests available, the number of people going for these screening tests are very low [22]. This is rather alarming and many studies have been conducted worldwide to discover and analyze the causes of low

A majority of the studies found that the largest barrier towards colorectal cancer

screening is poor knowledge of the general public towards the risk factors,

required and patient is usually able to return to work post procedure.

extra-colonic pathological findings that may arise [19, 20].

**4. Colorectal cancer screening uptake**

**5. Barriers for colorectal cancer screening**

turnout for colorectal cancer screening [23].

**5.1 Poor knowledge of CRC symptoms and risk factors**

the lowest rates [21].

**7**

and in a screening setting.

*Public Health: Prevention*

**3.5 Computed tomographic Colonography (CTC)**

*DOI: http://dx.doi.org/10.5772/intechopen.94396*
