Screening guidelines for colorectal cancer.

A review is given of methods and results of screening for colorectal cancer in average-risk and high-risk groups. Possible methods are digital rectal exploration, endoscopic examination, barium enemas, faecal occult blood tests, tumour markers like carcinoembryonic antigen, Ca-19-9, and others, and gene markers. Final results of large randomized population studies with faecal occult blood tests are expected within the next few years, but it will probably be necessary to add flexible sigmoidoscopy to achieve a major reduction in mortality from colorectal cancer in average-risk persons. Recommendations for screening in high-risk groups are proposed, but strong support for these guidelines are still missing, an exception being first-degree relatives of individuals with familial adenomatous polyposis; the other high-risk groups include members of hereditary non-polyposis colorectal cancer families, relatives of patients with sporadic colorectal cancer, patients with colorectal adenomas, patients with previous colorectal cancer, and patients with inflammatory bowel disease.