[Are chronic inflammatory bowel diseases precancerous conditions?(author's transl)].

Cancer risk in patients with ulcerative colitis is higher than in patients with Crohn's disease, the reason for this difference being unknown. In ulcerative colitis the risk of malignancy justifies a prophylactic colectomy when the disease begins in childhood or in adolescence involving the total colon and lasting for more than 10 years. In Crohn's disease malignant tumors have been described in 43 cases of terminal ileitis and in 32 cases of granulomatous colitis. The cancer risk is low and does not justify a prophylactic colectomy.