4:03 PM Abstract No. 247 Surveillance, Epidemiology, and End Results (SEER) survival study of stage T1a renal cell carcinoma treated with ablation vs. partial nephrectomy: a propensity-matched analysis

Abstract

To analyze survival in stage T1a renal cell carcinoma (RCC) treated with ablation compared to partial nephrectomy, using the Surveillance, Epidemiology, and End Results (SEER) database. Using the SEER database, we identified cases of diagnosed RCC who underwent partial nephrectomy or ablation between 2004 and 2013. Patients were included if they had a mass <4 cm and had partial or subtotal nephrectomy. We excluded patients with tumor extension outside the kidney or any nodal or distant metastases. Descriptive statistics were performed with Chi-squared and Wilcoxon sum rank tests for categorical and continuous variables respectively. Kaplan-Meier (KM) statistic and cox proportional hazards regression (CR) were performed. Propensity score matching (matched by age, sex, race, grade, tumor size, and tumor extension) was used to reduce treatment-selection bias and match pairs of subjects with similar background variables. KM and CR analyses were repeated after propensity matching. A total of 4592 patients were included (809 receiving ablation and 3783 receiving partial nephrectomy). Patients who underwent ablation were more likely to be older, with larger tumors, and lower tumor grade. Before propensity matching, there was significantly better overall survival (OS) and cancer-specific survival (CSS) in the partial nephrectomy group (93.6% 5-year survival) compared to the ablation group (81.9% 5-year survival) with p<0.0001. Propensity matching generated 1222 matched pairs with similar background characteristics in all background variables. Again, there was better OS in the partial nephrectomy group (91.0% vs 86.3% 5-survival, p = 0.0457), but the curves are not as divergent as in the pooled cohort. However, there is no significant difference in CSS between the treatment groups (p = 0.4023) in the propensity matched cohort. In this propensity-matched population study of stage T1a RCC, partial nephrectomy offers slightly better OS but similar CSS compared with ablation.