Screening for early colorectal cancer

There is now solid evidence from randomized trials suggesting that it is po ssible to reduce mortality from colorectal cancer by 15% to 25% by screenin g with fecal occult blood tests (FOBTs), The major benefit results from det ection of early canter in average-risk persons above 50 years of age who ha ve a positive test followed by colonoscopy, However, it has to be demonstra ted that the same acceptability ran be reached in the general population as that obtained in trials. Many countries must establish a screening organiz ation in a limited area to learn how satisfactory quality assurance can be obtained before a country-wide screening program is set up. So far, screeni ng has not resulted in a reduced incidence of colorectal cancer in true pop ulation studies despite removal of two to three times as many possible prec ursors compared to controls. Cost-effectiveness will probably be as good as that known from screening for breast cancer with mammography and better th an that for cervical cancer. However, the calculations are based on the unh ydrated Hemoccult-II test in randomized trials. More sensitive methods woul d be attractive, but none has yet been evaluated properly in average-risk p ersons. There is no general agreement how to screen high risk groups such a s patients with previous colorectal adenomas and carcinomas, one or two fir st-degree relatives with colorectal neoplasia, or ulcerative colitis. Famil ies with familial adenomatous polyposis or hereditary nonpolyposis colorect al cancer, however, are presented with firm guidelines. Genetic screening h as been helpful in no more than these two small groups in the colorectal ca rcinoma universe.