Screening for Early Colorectal Cancer

There is now solid evidence from randomized trials suggesting that it is possible to reduce mortality from colorectal cancer by 15% to 25% by screening with fecal occult blood tests (FOBTs). The major benefit results from detection of early cancer in average-risk persons above 50 years of age who have a positive test followed by colonoscopy. However, it has to be demonstrated that the same acceptability can be reached in the general population as that obtained in trials. Many countries must establish a screening organization in a limited area to learn how satisfactory quality assurance can be obtained before a country-wide screening program is set up. So far, screening has not resulted in a reduced incidence of colorectal cancer in true population studies despite removal of two to three times as many possible precursors compared to controls. Cost-effectiveness will probably be as good as that known from screening for breast cancer with mammography and better than that for cervical cancer. However, the calculations are based on the unhydrated Hemoccult-II test in randomized trials. More sensitive methods would be attractive, but none has yet been evaluated properly in average-risk persons. There is no general agreement how to screen high risk groups such as patients with previous colorectal adenomas and carcinomas, one or two first-degree relatives with colorectal neoplasia, or ulcerative colitis. Families with familial adenomatous polyposis or hereditary nonpolyposis colorectal cancer, however, are presented with firm guidelines. Genetic screening has been helpful in no more than these two small groups in the colorectal carcinoma universe.