J. R. Van Roo1, B. L. Miller1, T. J. Ziemlewicz2, S. L. Best1, S. A. Wells2, M. G. Lubner2, J. Hinshaw2, F. Shi1, F. T. Lee, Jr.2, S. Y. Nakada1, E. Abel1 1University Of Wisconsin,Department Of Urology,Madison, WI, USA 2University Of Wisconsin,Department Of Radiology,Madison, WI, USA
Introduction:
Approximately 15-20% of renal masses are classified as oncocytomas, oncocytic neoplasms or chromophobe renal cell carcinomas (chRCC). Historically, oncocytic renal neoplasms were excised because of the risk for RCC and because definitive diagnosis of benign tumors was difficult. However, thermal ablation and surveillance have emerged as alternative treatment options for renal masses over the last decade. The purpose of this study is to evaluate outcomes for surgery, ablation, and active surveillance of oncocytic neoplasms.
Methods:
Patients with pathologic diagnosis of renal oncocytic neoplasms from 2003-2016 were identified. Clinical, radiologic and pathologic data were collected for each patient. Oncologic outcomes, adverse events classified using Clavien system within 90 days of treatment, and renal functional outcomes were compared among patients treated surgically, using thermal ablation or with surveillance.
Results:
A total of 165 patients were identified with oncocytic renal masses including: 117 oncocytoma, 2 oncocytic neoplasms and 46 chRCC. Median tumor diameter was 2.9 cm [IQR 2-3.2] and median age was 67.3 years. A total of 131 (79.4%) patients were asymptomatic at presentation. Charlson Comorbidity Index(CCI) was 0 in 65(39.4%) and ≥1 in 98(59.6%). Patients treated surgically were more likely to have larger tumor diameter compared to other modalities (p=<.0001). Patients treated surgically or with ablation were older and had higher CCI when compared with patients undergoing active surveillance. (p<0.01, 0.02)
Definitive management included surgery for 77(46.7%), thermal ablation in 32(19.4%), and active surveillance in 56(33.9%). Median follow-up interval from diagnosis is 41 months [IQR 14-74]. Outcomes are displayed in table. A total of 3(1.8%) patients developed metastatic RCC (mRCC), and 2(1.2%) patients have died of disease. In patients who developed mRCC, tumor size at presentation was 5,10, 13 cm and all patients were symptomatic at presentation.
Patients treated surgically had higher rates of complications and longer length of hospitalization (p<0.01, <0.01). Patients treated with radical nephrectomy were more likely to have decreased renal function and 13(7.9%) patients died from other causes during surveillance.
Conclusion:
Renal oncocytic neoplasms have low metastatic potential overall. Active surveillance and thermal ablation should be considered for patients with oncocytic tumors <4cm.
