Carcinoma of the colon arising at ureteral implant sites despite early external diversion: pathogenetic and clinical implications.

Colon carcinomas develop at the site of implantation in approximately 6% of patients who undergo ureterosigmoidostomy for benign conditions. Generally, the obstruction of a long-functioning ureterosigmoidostomy heralds the presentation of the malignancy. The development of a carcinoma of the colon at the site of the ureteral stump 22 years after conversion to ileal conduit in a ureterosigmoidostomy, which had been in place for only nine months, raises fundamental questions about the pathogenesis of the tumor. The long-assumed role of urine in the induction of these iatrogenic tumors must be questioned. This issue and suggestions for management and prevention are discussed.