Νew Molecular Biomarkers for the Prevention and Early Detection of Precancerous or Cancerous Colorectal Lesions During Screening for Colorectal Cancer

Colorectal cancer (CRC) is the third most frequent cancer worldwide with a prevalence of 1.5 million people / year and is the second cause of death from cancer (650 000 deaths per year) for both genders after lung cancer.

In Greece it is estimated that about 3000 people are infected annually by the CRC. Risk factors for the emergence of CRC are: old age, positive family history of cancer and colon polyps, diet poor in fiber and rich in high-calorie fats and foods, sedentary lifestyle and lack of exercise from everyday life. Additionally, obesity, smoking, alcohol consumption in large quantities, diabetes, inflammatory conditions of the intestine such as ulcerative colitis and Crohn's Crohn, and some inherited disorders affecting colon are factors that increase the risk for the CRC.

It is a silent and insidious disease since most patients do not present symptoms in the early stages (such as bleeding, abdominal pain), resulting in diagnosis in a non-curable phase. This makes it clear that survival depends on the stage of disease at time of diagnosis. For example a patient with cancer Dukes' stage A, 5-year survival is about 93% whereas stage C, is about 47%. Based on the above it is clear that early detection of precancerous colorectal lesions is the cornerstone for the optimal treatment of this disease.

The CRC is an ideally disease to implement mass screening in general population as it follows a specific development process that lasts 7-12 years, leading to transformation of normal epithelium to adenoma and eventually carcinoma.

There are multiple options available for CRC detection involving the detection of blood in fecal test (or microscopic examination of fecal hemoglobin), the flexible sigmoidoscopy and colonoscopy. Each of these has advantages and disadvantages. Specifically, the microscopic examination of fecal hemoglobin although reduces mortality by 16% by CRC nevertheless exhibits low sensitivity to detect polyps and cancerous lesions in the distal colon and small specificity thus be, in economic terms, negative test to be used in mass screening. Regarding the flexible sigmoidoscopy, this is a test clearly faster and safer than colonoscopy but with small percentage of patient compliance, efficacy clear depended on the quality of bowel preparation and most importantly, it can not see the whole intestine. Computed tomographic colonography is another method of finding new precancerous lesions but because of the short diagnostic accuracy compared to the colonoscopy and radiation, is not recommended for mass screening.