De Novo Renal Cell Carcinoma of Native Kidneys in Renal Transplant Recipients: A Single-center Experience.

BACKGROUND: The risk of renal cell carcinoma (RCC) development in renal transplant recipients is 15-100 times higher than in the general population. The majority of RCCs found in renal transplant recipients develop in the recipient's native kidneys, only 9% of tumors develop in the allograft itself. The mechanisms of development of RCC in native kidneys and renal allografts are not completely understood. We present our experience in renal transplant recipients with RCC of native kidneys providing valuable and clinically applicable treatment and follow-up data.

PATIENTS AND METHODS: The records of 2,173 patients who underwent renal transplantation in our Department between March 1983 and December 2015 were retrospectively reviewed. Using these data, we analyzed the incidence and types of post-transplant RCCs, as well as their clinical courses, focusing on native malignancies.

RESULTS: We found 11 RCCs (0.5%) during the observation period in native kidneys. The mean (±SD) follow-up period was 50.54±32.80 months. Four patients died during this period (36.4%).

CONCLUSION: Most RCCs in renal transplant recipients are low-stage, low-grade tumors with a favorable prognosis. Their diagnosis is usually incidental. RCC development in the native kidney of renal transplant recipients is an early event, frequently observed within 4 to 5 years after transplantation. The different natural history of these tumors is still undefined. Further research is needed to determine whether these differences are due to particular molecular pathways or to biases in relation to the mode of diagnosis.