Incidence of colonic cancer in inflammatory bowel disease

In a cohort of 783 regional patients with ulcerative colitis treated in specialized clinics from the onset of the disease, the intestinal cancer risk was estimated. Seven patients developed colonic cancer from 4 to 44 years after onset of disease (median, 14 years). Eighteen years after onset of the disease the calculated risk was 1.4% (0.7-2.8%). After completing this follow-up study a new study was carried out with colonoscopy of all long-standing cases (greater than or equal to 15 years) of ulcerative colitis which had not been operated on. Of 100 patients examined, 2 showed epithelial dysplasia, and 98 did not. In a similar cohort of 185 patients with Crohn's disease, 1 showed small-bowel cancer. This gives a calculated risk of 0.6% (0.1-3.1%) at 10 years after the disease onset.