Sirolimus Does Not Absolutely Abolish the Occurrence/Recurrence of Urothelial Carcinoma in Renal Transplant Recipients

Objective: Sirolimus (SRL), an immunosuppressant shown to possess anti-proliferative properties, was hypothesized to mitigate the occurrence of posttransplantation malignancy. We examined its effect on posttransplantation urothelial carcinoma (UC). Methods: This retrospective case analysis included renal allograft recipients with UC treated with SRL in a single institute. Results: Among 90 renal recipients treated with SRL, 6 had previous/new-onset UC in the native kidney/ureter or bladder: at a mean period of 28 months (range, 7-49) of administering SRL for these recipients, UC occurred/recurred in 4 of the 6 patients. Individual cases are presented in detail. Conclusion: SRL does not absolutely abolish the occurrence/recurrence of UC among renal transplant recipients. Its potency as an anti-cancerous immunosuppressant for transplant recipients with UC deserves to be further defined in larger studies, probably by controlling SRL blood levels at lower or much higher ranges than used herein.