Cancer in Crohn's disease. The danger of a by-passed loop.

Carcinoma developed in an excluded segment of small bowel in an 80-year old male patient, 40 years following the onset of regional enteritis and 33 years after by-pass of the terminal ileum. Within the past four years, four patients with malignancy occurring in excluded segments of the bowel in Crohn's disease have been reported from the institution. Two occurred in the small bowel and two in the colon. In three patients the lesion was associated with enterovesical fistula suggesting a possible relationship. This complication stresses the need to encourage resection rather than by-pass of all inflammatory lesions and to view all long-standing by-passed loops of intestine with suspicion. An international tumor registry of cancer in Crohn's disease is desirable to continue to document the true incidence of cancer in Crohn's disease.