Is Active Surveillance a Suitable Approach for Bilateral Multifocal Renal Oncocytomas? The 20-Year National Cancer Institute Experience.

Objectives: To investigate the clinical characteristics, tumor growth rate, oncologic and renal function outcomes in patients with bilateral, multifocal renal oncocytoma managed with active surveillance and/or surgery.

Materials And Methods: Bilateral, multifocal renal oncocytoma patients were evaluated using clinical, cross-sectional imaging and pathologic records. The cohort was divided into 3 groups: those under active surveillance only, those who underwent surgery in combination with active surveillance, and those who underwent multiple interventions. Growth rate, metastases and renal function outcomes were compared between the 3 groups.

Results: Sixty-two patients (median age 64 years (IQR 57.5-69), 49 men) were identified with 10 patients (16.1%) having a known family history of bilateral, multifocal oncocytoma. Overall, the combined median growth rate of primary tumors across all 3 groups was 0.25 cm/year (IQR 0.1-0.4). Comparing between all 3 groups identified a statistically significant difference in age of diagnosis (P = .01), whereas no difference was noted for age at death. No distant metastasis was observed. A statistically significant difference in median tumor size at the time of last follow-up (P = .02) was reported among the 3 groups. No statistically significant differences were seen in primary tumor growth rate (P = .50), initial eGFR (P = .35), final eGFR (P = .26) and change in eGFR levels over time (P = .10) among all 3 groups.

Conclusion: Disease-specific outcomes and renal function outcomes do not differ significantly among the patients managed with active surveillance and/or surgery.