Long-Term Clinical Outcomes Following Radiofrequency and Microwave Ablation of Renal Cell Carcinoma at a Single VA Medical Center.

Abboud, Salim E; Patel, Tanay; Soriano, Stephanie; Giesler, Joseph; Alvarado, Nannette; Kang, Preet

PURPOSE Microwave ablation (MWA) is a relatively newer treatment modality for treatment of renal cell carcinoma (RCC), and only a few small studies have examined the short- and long-term outcomes for MWA applied to renal tumors. The purpose of this retrospective review is to assess the initial experience including technical short- and long-term success rates of using radiofrequency ablation (RFA) and MWA for RCC at a single Veterans Affairs (VA) medical center. MATERIALS AND METHODS Tumor characteristics were recorded using the R.E.N.A.L. nephrometry score. Group comparisons were performed by using univariate logistic regression analysis to determine factors affecting primary treatment success, failure, and effectiveness. Kaplan-Meier local tumor progression-free survival following ablation was calculated. RESULTS MWA and RFA groups were not significantly different in primary treatment success (P = 0.82). MWA primary treatment success (90.2%) was not associated with R.E.N.A.L criteria, whereas primary success in the RFA group (88.2%) was predicted by smaller tumor size (P = 0.002). Primary treatment effectiveness rates were not significantly different in MWA (88.2%) and RFA (80.3%) groups (P = 0.29). Although overall primary technique effectiveness was associated with size (P = 0.02), univariate analysis showed a significant association between tumor size and primary effectiveness for RFA (P = 0.002) but not MWA. There was no significant association between R.E.N.A.L score or criteria and primary treatment effectiveness in the RFA or MWA groups. CONCLUSION RFA and MWA both represent effective treatment modalities for RCC; larger tumor size may be associated with decreased efficacy of thermal ablation techniques.