Safety and Clinical Outcomes of Percutaneous Radiofrequency Ablation for Intermediate and Large Bone Tumors Using a Multiple-Electrode Switching System: A Phase II Clinical Study.

PURPOSE: To evaluate the safety and clinical outcomes of radiofrequency (RF) ablation using a multiple-electrode switching system in patients with bone tumors > 3 cm. MATERIALS AND METHODS: This prospective study enrolled 20 subjects (15 men, 5 women; mean age 70.0 y ± 7.4 [SD]; range, 60-80 y) with malignant unresectable bone tumors. The maximum mean tumor diameter was 5.5 cm ± 2.0 (range, 3.1-10.0 cm). Two to three RF electrodes were placed into each bone tumor. Real-time CT fluoroscopic guidance was used with a multiple-electrode switching system. The primary endpoint was safety, as evaluated by Common Terminology Criteria for Adverse Events, until 12 months after bone RF ablation. As secondary endpoints, pain relief was evaluated by visual analog scale (VAS) scores before and 1 week after RF ablation; tumor response, by contrast-enhanced magnetic resonance imaging studies until 4 weeks after bone RF ablation; and survival, by Kaplan-Meier method. RESULTS: No adverse event was found in 19 of 20 patients (95%). Grade 2 fever occurred in 1 patient (5%; 1/20). VAS scores decreased by ≥ 2 in 11 of 13 patients (84.6%) who had painful bone tumors. Tumor response (complete or partial response) was achieved in 16 of 18 patients (88.9%) who underwent follow-up imaging studies. The 1-year overall survival rate was 60.9%, and the median survival time was 14.1 months. CONCLUSIONS: Bone RF ablation using this system is safe and achieves local tumor control and pain relief in patients with large bone tumors.