Colorectal cancer (CRC) is the fourth commonest form of cancer occurring worldwide. CRC is an important public health problem: CRC is the second most common cause of cancer mortality. The incidence of CRC increases with increasing age. Approximately 50% of CRC cases are diagnosed at distant stage. Screening for CRC can reduce incidence by preventing cancer occurrence through the detection and removal of precancerous polyps.

The main risk factors for CRC include:
• Diets low in vegetables and potentially, those high in processed meat and fat
• Excess body weight
• Lack of exercise
• Smoking
• Drinking excess alcohol

• Inherited factors:
• • Familial Adenomatous Polyposis (FAP)
• • Hereditary Non-Polyposis Colorectal Cancer (HNPCC)
• • “Cancer family” syndrome

• Inflammatory bowel disease.

How individuals can reduce their risk of CRC is summarized below:
• Increase intake of vegetables and fruits
• Reduce intake of calories (animal fats in particular)
• Increase physical activity
• Stop smoking
• Decrease alcohol consumption
• Consult a doctor as soon as possible if blood is present in the stool, a noticeable and unexplained change in bowel habits occurs, colicky pain occurs in the abdomen, or a sensation of incomplete evacuation after defecation recurs
• Participate in population-based screening programmes
• Strongly consider having a colonoscopy starting from 50 years of age.

CRC can take many years to develop and early detection of colorectal adenomas and colorectal cancer greatly improves the chances of a cure. Therefore CRC screening is recommended in all individuals who are at increased risk and in subjects aged over 50 years.
There are two main tests available for this purpose.

• Colonoscopy: is the gold standard for the diagnosis and for screening. A lighted probe called a colonoscopy is inserted into the rectum and the entire colon to look for adenomas (polyps) and other abnormalities that may be caused by colorectal cancer. Colonoscopy has the advantage that if polyps are found during the procedure they can be immediately removed. In addition, tissue can also be taken for biopsy; the tissue sample is then tested with a microscope.
• Fecal occult blood test (FOBT): a test for blood in the stool. After a positive test a colonoscopy should always be performed.