Cancer prevention in inflammatory bowel disease and the chemoprophylactic potential of 5-aminosalicylic acid.

The risk of colorectal cancer is increased in ulcerative colitis and Crohn's colitis. Regular dysplasia surveillance colonoscopy in chronic colitis generally has been adopted as a strategy to prevent colorectal cancer or at least to diagnose it in an earlier stage. This has not been proven to reduce mortality, but it does provide the clinician and the patient with some confidence that they are participating in an active strategy to deal with the problem of colorectal cancer in chronic colitis. Disease extent and duration have long been held to be risk factors for colorectal cancer in chronic colitis, and recently some special risk groups have been identified which may require either more intensive surveillance or alternative approaches to cancer prevention. These include patients with primary sclerosing cholangitis, patients with first-degree relatives with sporadic colon cancer, and possibly, patients with backwash ileitis. There is an emerging interest in potential chemopreventative strategies in both sporadic and colitis-associated colorectal cancer. There also have been suggestive data that chronic maintenance 5-aminosalicylate use might reduce the risk of developing colorectal cancer. Recent data have suggested some potential preventative benefit of using ursodeoxycholic acid in patients with ulcerative colitis and primary sclerosing cholangitis. The scientific rationale for using these agents is sound but clinical data are lacking to fully support these approaches as chemoprevention in chronic colitis at present.