Crohn's disease and adenocarcinoma of the bowel.

We present six cases of cancer associated with Crohn's disease and stress the importance of the earlier age of onset than spontaneously arising small-bowel carcinoma, the long period of latency from the time of diagnosis of Crohn's disease to that of carcinoma, and the generally poor prognosis. We emphasize, furthermore, the frequent association with fistulas and the predisposition of bypassed or excluded segments of bowel to undergo malignant transformation. The occurrence of carcinoma in an excluded rectal stump has not previously been reported and stresses the necessity of resecting, rather than excluding, segments of bowel involved with Crohn's disease. These tumors are often not readily apparent by radiographic or endoscopic examination and in fact, may be discovered only after microscopic examination of resected or biopsied tissue.