SAN DIEGO—Patients who undergo renal transplantation are at increased risk of papillary renal cell carcinoma (RCC) developing in the allograft, according to study findings presented at the American Urological Association 2016 annual meeting.

In a review of 56 published studies examining the incidence of solid renal masses (SRMs) in kidney allografts, John Griffith, MD, a third-year resident at the Icahn School of Medicine at Mount Sinai in New York, and colleagues found that the incidence of papillary RCC was significantly greater in allograft kidneys than in the non-transplant population (42% vs 10%–15%.

“As life expectancy improves for renal transplant patients, SRMs will likely become more prevalent,” the researchers concluded in their study abstract. “Proper surveillance of this subpopulation is imperative, as acceptable oncological outcome of allograft tumors is achievable.”

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The 56 studies included 163 patients with 174 SRMs. The mean tumor size was 2.75 cm. Among the 164 tumors for which histologic finding were available, 45.7% were clear-cell RCC, 42.1% were papillary RCC, 3% were chromophobe RCC, and 9.1% were other histologies. The tumors were managed by partial nephrectomy (67.5%), radical nephrectomy (19.4%), percutaneous radiofrequency ablation (10.4%), and cryoablation (2.4%).

In an interview with Renal & Urology News, Dr Griffith said he and his colleagues are unable to explain why only papillary RCC and no other histologic variant occurs at a higher incidence in renal allografts compared with the non-transplant population, but they hypothesize that this is related to chronic immunosuppression. The finding “certainly has significant implications in terms of management” because papillary RCC tends to be multicentric. In addition, if the allograft came from a living donor, clinicians would want to contact that donor and decide on a screening mechanism to see if a renal mass develops in the patient’s now-solitary kidney.