**The Role of Colonoscopy in the Prevention of Colon and Rectal Cancer**

David Martínez Ares and Pamela Estévez Boullosa *Gastroenterology Unit. Complejo Hospitalario Universitario de Vigo, Vigo-Pontevedra Spain* 

### **1. Introduction**

Colorectal cancer (CRC) is one of the most common tumors in our society. It is the most common gastrointestinal tumor and it is also estimated that between 5 and 6% of the population will suffer this tumor along their lives. Colorectal cancer is a tumor in which it is possible to perform primary and secondary prevention. It ranks second in frequency in both men and women, and it represents the second leading cause of cancer-related deaths in both men (after lung cancer) and women (after breast cancer). Indeed, CRC is responsible for 12% of cancer-related deaths in men and for 15% in women. It represents, therefore, a public health problem of first magnitude, causing over 10,500 annual deaths in Spain; so it is well established and cost effectiveness to use a program for early detection and prevention of this disease. CRC mortality in 2006 was almost double that the one recorded in Spain in 1975 in both sexes, considering them separately, and in the entire population as a whole. In relation to the rest of the Europe, Spain has an intermediate CRC mortality, lower than that recorded in Czech Republic or Slovakia, and well above from CRC mortality in Finland or Cyprus. In Spain, cancer mortality is higher in the north than in the south, and this difference is more significant in males. Furthermore, cancer mortality in the whole country is quite stable since the beginning of this century, observing a slight increase in northern regions.

The survival of patients diagnosed with CRC is approximately 54% at 5 years after diagnosis. However, survival is significantly lower in the group of patients in advanced stages, and much higher, with a survival rate around 90%, when it comes to patients in early stages. Therefore, an early diagnosis of colorectal cancer can lead to a significant reduction in cancer mortality. Consequently, a program of screening or early detection could considerably improve the prognosis of this disease.

Colorectal cancer is a health problem that fulfills all the requirements that the World Health Organization requires to consider a cost-effective screening program for early detection of neoplasia: first it is a very common disease, representing a major public health problem; second it is a disease with a well-known natural history, fulfilling in most cases the adenoma-carcinoma sequence (Figure 1), and this natural history is long enough so it can be interrupted by various diagnostic and therapeutic strategies; thirdly, we have diagnostic methods with enough diagnostic accuracy and at reasonable cost; fourthly, there is an effective treatment and, finally, this approach seems to be cost-effective. However, these screening programs have been implemented in very few sites in the world, having to be reduced in many cases to opportunistic screening or, at best, reduced to population at

The Role of Colonoscopy in the Prevention of Colon and Rectal Cancer 197

Colonoscopy plays a dual role in preventing colorectal cancer. First, endoscopic examination of the colon and rectum is the gold standard in the diagnosis of neoplastic and preneoplastic lesions in the large intestine. On the other hand, the development of therapeutic techniques such as polypectomy or more complex techniques like endoscopic mucosal resection or endoscopic submucosal dissection, allows the removal of some of these lesions. Indeed, endoscopic resection is curative in almost all preneoplastic lesions (benign lesions) and may be curative in early malignant lesions, which are those that only affect the mucosa and

Colonoscopy is useful for the diagnosis of cancer and precancerous lesions. Unquestionably, despite radiological techniques are useful for diagnosis, the role of colonoscopy is essential firstly to confirm the radiological findings and also to obtain biopsy specimens for histological diagnosis. Colorectal cancer is frequently presented as proliferative lesions that produce some stenosis of the intestinal lumen, with ulcerated surface and even with hemorrhagic necrotic areas (Figure 2); sometimes they are polypoid lesions that can also

have ulcerated areas (Figure 3), or just be circumscribed ulcerations (Figure 4).

Fig. 2. Malignant lesion covering the entire circumference that produces stenosis of the intestinal lumen, with ulcerated surface, hemorrhagic necrotic areas and bleeding easily at

**2. The role of colonoscopy in preventing colorectal cancer** 

submucosa.

the touch of endoscope

highest risk of developing the disease, such as those suffering from predisposing diseases such as ulcerative colitis, or individuals with high familial risk of developing the disease.

There is little doubt about the beneficial of a program for early detection of colon cancer: the diagnosis of the disease in an early stage practically ensures its cure, and even in many cases, we will be able to diagnose precancerous lesions and removing them we can avoid the appearance of cancer. The best prevention strategy is subject of discussion, especially in lower-risk patients.

As expected, before proposing an individual for inclusion in a screening program it is essential to establish their individual risk of developing colon cancer. Routinely, the population is divided into three groups according to their risk of developing colorectal cancer (CRC):


Fig. 1. Adenoma-carcinoma sequence represents the evolution of most colorectal carcinomas, from a normal colon to the development of an invasive carcinoma

highest risk of developing the disease, such as those suffering from predisposing diseases such as ulcerative colitis, or individuals with high familial risk of developing the disease. There is little doubt about the beneficial of a program for early detection of colon cancer: the diagnosis of the disease in an early stage practically ensures its cure, and even in many cases, we will be able to diagnose precancerous lesions and removing them we can avoid the appearance of cancer. The best prevention strategy is subject of discussion, especially in

As expected, before proposing an individual for inclusion in a screening program it is essential to establish their individual risk of developing colon cancer. Routinely, the population is




Fig. 1. Adenoma-carcinoma sequence represents the evolution of most colorectal carcinomas, from a normal colon to the development of an invasive carcinoma

divided into three groups according to their risk of developing colorectal cancer (CRC):

age, it is justified to perform an early diagnosis.

lower-risk patients.

screening.

common).
