No difference in renal function outcomes for patients with oncocytoma managed with active surveillance vs. partial nephrectomy

Objectives: To investigate the difference in renal function outcomes for patients with oncocytomas undergoing active surveillance (AS) vs. partial nephrectomy (PN). Methods: We reviewed our institutional database for patients with biopsy/surgically confirmed oncocytoma from 2000-2020. The primary outcome was to assess for differences in renal function outcomes in patients undergoing AS vs. PN. We fit two generalized estimating equation (GEE) with an interaction term between follow up time and management strategy to predict 1) mean eGFR for patients managed with AS and PN and 2) the probability of progression to CKD stage III or greater. Results: We identified 114 eligible patients, of which 32 were managed with AS. Median follow-up was 21 months vs. 44 months for PN vs. AS patients. AS patients tended to be older (median: 72 years vs. 65 years, P<0.001) and have lower baseline renal function (median: eGFR: 71 mL/min/1.73m² vs. 82 mL/min/1.73m², P<0.001) compared with PN patients. Renal mass size from baseline imaging was similar between patients undergoing PN vs. AS (2.8 cm vs. 2.9 cm, P=0.634). For patients undergoing PN vs. AS, there was not a significant difference in predicted longitudinal eGFR (-0.079, 95% CI -0.18-0.023, P=0.129) or predicted probability of progression to CKD stage III or greater (OR: 0.61, 95% CI: 0.16-2.33, P=0.47). Conclusions: In our institutional dataset, patients undergoing AS or PN with an oncocytoma had similar long-term renal function outcomes. Given similar renal function outcomes in patients undergoing AS and PN, surgery should remain reserved for select patients with oncocytomas.