Carcinogenesis at colonic anastomotic sites

For three months 65 male Sprague-Dawley rats received subcutaneous 1,2-dimethylhydrazine (DMH) weekly. Of the 65 animals, 45 were subjected to resection of the transverse colon, which subsequently was stitched to the abdominal wall. The remaining 20 animals were sham-operated controls. Fifty-four per cent of the tumors occurred either at the anastomotic site in the functioning colon (31 per cent) or at the anastomotic site of the isolated and defunctionalized colonic loop (23 per cent). On the other hand, only 10 per cent of the tumors occurred in the transverse colon of sham-operated controls. The difference was significant (P less than 0.001).