Tumour formation within intestinal segments transposed to the urinary tract.

Patients and their urologists are quite rightly concerned about the possibility of neoplastic change within intestinal segments transposed to the lower urinary tract. This fear arises from the occurrence of latent adenocarcinoma arising from the urocolic anastomosis in approximately 10% of patients who underwent ureterosigmoidostomy in childhood. The present text provides an update of previous reviews and details work published since 1990 on epidemiological, experimental and clinical studies. Consideration of the collected evidence confirms the increased risk of colonic neoplasia following mixing of the faecal and urinary stream by ureterosigmoidostomy or its more recent variants. In contrast, the occurrence of tumours within transposed intestinal segments appears more likely to be related to the underlying urinary tract disease for which the surgery was performed rather than exposure of the intestinal mucosa to urine. This conclusion is, however, based on low level evidence and, despite the reassuring findings, caution is advised until more robust data are available to provide a confident risk assessment.