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MP42-16 TREATMENT OF VERY SMALL RENAL MASSES IN THE UNITED STATES

INTRODUCTION AND OBJECTIVES: Management of small renal masses (SRMs) has changed over the past two decades with the diffusion of minimally invasive techniques and establishment of thermal ablation and active surveillance as management strategies. Very small renal masses (vSRMs, ⩽2.5cm) exhibit slow growth kinetics and low metastatic potential. Nephron sparing (NS) techniques (ablation or partial nephrectomy) or surveillance are recommended for management of vSRMs. We evaluate practice patterns for vSRMs in a national database that captures 70% of all cancer diagnoses in the US. METHODS: We identified patients with non-metastatic vSRMs from 2004 - 2015 from the NCDB. Treatment codes were divided into no surgery, partial nephrectomy, total nephrectomy, or ablation. Temporal trends were assessed using Pearson's correlation coefficient. We identified socioeconomic and clinical factors associated with NS interventions. RESULTS: 67,740 patients met inclusion criteria. 10,588 (16%) underwent ablation, 35,991 (53%) had partial nephrectomy, 13,535 (20%) had total nephrectomy, 7,626 (11%) did not have any procedure. Treatment type by time (both by number and proportion) is shown in Fig.1. On multivariable analysis, significant factors associated with ablation compared to surgery were age, race, facility volume, type of institution, insurance, and region. Among surgery patients (n=49,526), significant factors associated with partial nephrectomy included age, race, facility volume, and type of institution. Utilization of NS procedures increased in the study period: from 43% to 56% for partial nephrectomy and from 9% to 16% for thermal ablation, (p<0.001 for both). CONCLUSIONS: Utilization of NS procedures for vSRMs has significantly increased over the past decade. Rates of thermal ablation and partial nephrectomy increased initially, but have remained stable recently. Total nephrectomy for vSRMs decreased over the study period, likely due to advances in understanding the generally indolent behavior of vSRMs and the consequences of renal insufficiency. However, overtreatment of vSRMs with total nephrectomy persists, accounting for 14% of all treatment from 2013-2015. Non-clinical, socioeconomic factors are also associated with treatment modality suggesting disparities in health care delivery in the US. Figure. No caption available. Source of Funding: none