[Colorectal cancer mortality can be reduced. Fecal blood screening is an efficient test].

Findings in large randomised studies in Europe and America show that colorectal cancer mortality can be reduced by faecal occult blood screening. Moreover, in the American study it was shown for the first time that the risk of colorectal cancer is reduced by removal of benign polyps larger than 9 mm. Partly as a result of uncontrolled studies showing repeat examination with the rigid rectoscope and removal of benign adenomas to reduce the risk of cancer, flexible sigmoidoscopy has been adopted in two controlled studies, one British the other American, though the problem remains of diagnosing the 30-40 per cent of tumours that are inaccessible to the sigmoidoscope. Together, the two types of hereditary colorectal cancer, familial adenomatous polyposis and hereditary non-polyposis colon cancer, account for only 5-10 per cent of all colorectal cancer, the overwhelming majority of cases being sporadic.