Renal Cell Carcinoma: Radiofrequency Ablation with a Multiple-Electrode Switching System-A Phase II Clinical Study

Purpose: To prospectively evaluate the safety and effectiveness of radiofrequency ablation with a multiple-electrode switching system for the treatment of renal cell carcinoma (RCC). Materials and Methods: From November 2009 to December 2010, 33 patients (mean age, 70.7 years; range, 44-86 years) with histologically proved RCCs-including 24 men (mean age, 69.5 years [range, 44-86 years]) and nine women (mean age, 74.1 years [range, 64-83 years])-were enrolled in this phase II study. The institutional review board approved the study after patients provided written informed consent. The mean maximum tumor diameter was 2.9 cm +/- 1.0 (standard deviation) (range, 1.5-5.0 cm). Radiofrequency ablation was conducted with a multiple-electrode switching system. The primary endpoint was evaluated with the Common Terminology Criteria for Adverse Events. Secondary endpoints were changes in renal function, technique effectiveness, local tumor progression, and survival. Changes in renal function were evaluated by using the Mann-Whitney U test. Results: No severe adverse events occurred, but three of 33 patients (9%) had grade 2 adverse events. Although the mean glomerular filtration rate at 1 year after radiofrequency ablation was similar to the baseline value in 26 patients with bilateral kidneys (P = .14), it was decreased significantly in six patients with a single kidney (P = .03). Tumor enhancement disappeared after a single radiofrequency session in 31 patients and after two radiofrequency sessions in the other two patients (rates of primary and secondary technique effectiveness, 94% [31 of 33] and 100% [33 of 33], respectively). No local tumor progression was found during the mean follow-up of 20.0 months (range, 11.6-27.6 months). The respective 1-year overall and RCC-related survival rates were 97% (95% confidence interval: 91%, 100%) and 100%. Conclusion: Radiofrequency ablation with a multiple-electrode switching system is safe and effective for treatment of RCCs. However, further study is warranted to determine whether this technology is superior to other previously described methods. (C)RSNA, 2013