How to manage renal masses in kidney transplant recipients? A collaborative review by the EAU-YAU kidney transplantation and renal cancer working groups.

INTRODUCTION: Kidney transplant (KT) recipients have a four-times higher risk of renal malignancies compared to general population. As these patients frequently harbor bilateral or multifocal tumors, the management of renal masses is still under debate. OBJECTIVE: To explore the current management of the native kidney masses in KT patients. ACQUISITION OF EVIDENCE: We performed a literature search on MEDLINE/PubMed database. A number of 34 studies were included in the present review. SYNTHESIS OF EVIDENCE: In frail patients with renal masses below 3 cm, active surveillance is a feasible alternative. Nephron-sparing surgery is not justified for masses in the native kidney. Radical nephrectomy is the standard treatment for post-transplant renal tumors of the native kidneys in KT recipients, with laparoscopic techniques leading to significantly less perioperative complication rates as compared to the open approach. Concurrent bilateral native nephrectomy at the time of transplantation can be considered in patients with renal mass and polycystic kidney disease, especially if no residual urinary output is present. Patients with localized disease and successful radical nephrectomy do not require immunosuppression adjustment. In metastatic cases, mTOR agents can ensure efficient antitumoral response, while maintaining proper immunosuppression in order to protect the graft. CONCLUSIONS: Post-transplant renal cancer of the native kidneys is a frequent occurrence. Radical nephrectomy is most frequently performed for localized renal masses. A standardized and widely-approved screening strategy for malignancies of native renal units is yet to be implemented.