Risks of intestinal cancer in Crohn's disease.

This review describes the principal features of the three studies that have established clearly that patients in the U.S.A. or the U.K. who have long-standing (greater than 7 years) Crohn's colitis are at increased risk (up to 20-fold) of developing large bowel cancer. In addition, it emphasizes that there are no data on the extent of this risk in patients in other countries, and also that the magnitude of the risk of cancer of the small intestine in Crohn's disease is unknown. Despite the increased incidence of large bowel cancer in long-standing Crohn's colitis in the U.S.A. or the U.K., the total number of such patients is small, as is the number in which the colonic carcinoma will occur. However, careful supervision is advised for the small group at risk, despite the limitations of current methods for the early detection of cancer of the large intestine.