To compare oncological and procedural outcomes for renal oncocytic tumors treated with surgery, thermal ablation, or active surveillance.

Clinical and pathologic data were collected for consecutive patients with a histologic diagnosis of oncocytoma, oncocytic neoplasm, or chromophobe renal cell cancer (chRCC) from 2003 to 2016. Independent pathology and radiology reviews were performed for this study.

Of 171 patients, tumor histology included oncocytoma (n = 122), chRCC (n = 47), and oncocytic neoplasm not otherwise specified (n = 2). At the initial diagnosis, 67, 14, and 90 patients were treated with surgery, thermal ablation, and active surveillance. In 3 of 19 patients (16%) who had biopsy and subsequent surgery, diagnosis changed from oncocytoma to chRCC. The median follow-up was 39.9 months with no difference among choices of treatment modalities (P = .33). Of 90 patients who began active surveillance, 32 (36%) switched to active treatments (19 underwent thermal ablation and 13 underwent surgery). The median linear growth rate for patients on active surveillance was 1.2 mm/y. No patients who were managed with active surveillance developed metastatic renal cell cancer (mRCC). mRCC was identified in 3 patients and was the cause of death in 2 patients. Patients who developed metastatic disease presented with symptomatic tumors of >4 cm and were treated with immediate surgery. For oncocytic masses of ≤4 cm (n = 126), the 5-year cancer-specific survival was 100%.

Renal oncocytic neoplasms have favorable oncological outcomes. Active surveillance is safe and is the preferred management for small (≤4 cm) oncocytic renal tumors in selected patients.