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

ABSTRACT

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.