Colorectal cancer risk after jejunoileal bypass: dysplasia and DNA content in longtime follow-up of patients operated on for morbid obesity.

Jejunoileal bypass (JIB) has been a widespread operation for treatment of morbid obesity. Bile acids are regarded as cofactors in the carcinogenesis of the colon, and, since intestinal bypass involves increased exposure of bile acids to the large intestinal mucosa, JIB has been postulated to increase the risk for colorectal carcinoma. In experimental studies on animals, the results have indicated an increased frequency of induced carcinomas, but in clinical series only one patient with colon carcinoma has been reported. Thirty women, operated on with JIB 11 to 17 years earlier, were examined by colonoscopy with multiple biopsies, systematically taken for histologic evaluation and flow cytometric DNA analysis. In only one patient, low-grade dysplasia was detected in an initial adenomatous lesion but was not visible macroscopically. No DNA aneuploidy was found. In a control group of 11 patients examined for non-neoplastic disease, neither dysplasia nor aneuploidy was diagnosed. Within 17 years postoperatively, we have, by these methods, not been able to verify any colorectal malignant transformation in patients operated on with JIB. However, since carcinogenesis is a long process, further surveillance will be demanded before an increased risk for colorectal carcinoma can be excluded.