Introduction: Partial nephrectomy (PN) represents the standard of care for localized kidney tumor. Nonetheless, a proportion of PN treated patients harbor benign histology (Bn) at final pathology report. Moreover, the contemporary surge in incidental diagnosis of renal masses may inadvertently increase the overall number of patients treated with PN for Bn lesion. Unfortunately, literature specifically addressing Bn tumors is scarce. To address this void, we investigated contemporary rates of Bn histology, as well as perioperative and functional outcomes of RAPN performed for Bn tumors. Methods: Whitin a multi-institutional database, we identified North American and European patients aged >18 years old treated with RAPN for localized renal masses (cT1-2) . Then, 1:1 PSM between malignant (Mn) vs Bn histology was performed adjusting for important confounders (age, sex, WIT, baseline eGFR, RENAL, BMI, ASA, Hypertension, Diabetes, solitary kidney status and multifocality). Cox regression model addressed any upstaging to CKD = 3a (CKD3a-upstaging) and to CKD = 3b (CKD3b-upstaging), linear model addressed length of hospital stay (LOS) and logistic regression model addressed any perioperative complications and postoperative Acute Kidney Injury (AKI). Results: Overall, 2256 patients were identified. Of those, 530 (23%) harbored Bn. The majority were oncocytoma (47.1%) followed by angiomyolipoma (39.4%). Baseline characteristics, perioperative and funcitonal outcomes were reported in Table 1. After PSM, no differences in CKD3a-upstaging (HR: 1.26 95%CI 0.87-1.81, p=0.2), CKD3b-upstaging (HR: 1.04 95%CI 0.57-1.91, p=0.9), LOS (estimate: -0.22 ± 0.21, p=0.3), any complications (OR: 1.14 95%CI 0.70 – 1.90, p=0.6) and postoperative AKI (OR: 0.97 95%CI 0.60 – 1.57, p=0.9) between Bn vs Mn were detected. Conclusions: Overall, more than one fifth of patients receiving RAPN for localized renal masses harbored Bn with a tiny percentage exhibiting high-grade complications. Despite accurate adjustments, Bn patients did not exhibit better outcomes than their Mn counterparts. Thus, these data are of primary importance when counseling patients treated with RAPN for Bn renal masses and questioned the benefit of RAPN as all-in-one strategy for diagnosis and treatment in those patients. SOURCE OF Funding: no
