Screening for colorectal cancer

Colorectal cancer is an ideal disease to be screened. It is the second most common cancer after lung and is the most common fatal malignancy in non-smokers. Colorectal cancer arises from a benign process, an adenoma or a polyp. A polyp is probably present for 10-20 years before it becomes malignant. Not all polyps become cancerous and it is not possible to predict with certainty which ones carry a malignant potential. However, in general, if polyps are multiple or larger than 1cm in diameter malignant change is more likely to occur. The finding of a polyp in the distal colon increases the chances of finding a polyp or cancer in the proximal colon. Furthermore, although distal hyperplastic polyps have been considered to be of little significance, there is data to suggest that their presence also increases the risk of developing a cancer in the proximal colon. If polyps are detected they can be removed by colonoscopic polypectomy. The knowledge that colorectal cancer starts as a benign process has stimulated an interest in screening to prevent colorectal cancer. In addition, numerous studies have shown that if colorectal cancer is detected early it can be cured.