Phase I/II Study of Radiofrequency Ablation for Painful Bone Metastases: Japan Interventional Radiology in Oncology Study Group 0208

Purpose: A prospective multicenter phase I/II trial was performed to evaluate the clinical safety and efficacy of radiofrequency ablation (RFA) for metastatic bone tumors. Materials and Methods: Thirty-three patients (27 men, 6 women, mean age 61 years) with metastatic bone tumors were enrolled. In phase I, nine patients were enrolled, and the safety of RFA was evaluated. In phase II, 23 patients were included, and an intent-to-treat analysis was performed. The primary endpoint was to evaluate the treatment’s safety. The secondary endpoint was to evaluate the efficacy of pain relief at 1 week after RFA. Results: RFA was performed in 32 of 33 enrolled patients. No serious complications were observed during the phase I, so phase II was performed. Four patients exhibited adverse events, including one case each of Grade 3 pain and, Grade 2 hypotension, and one patient developed Grade 1 burns at the grounding pad and puncture site. One patient died of liver failure on day 7 after RFA due to the progression of the primary lesion. The efficacy was excellent (no increase in analgesic dosage, post-RFA VAS score of 0–2 or decreased by not less than 5 compared to before RFA) in 20 patients (60.6%), good (no increase in analgesic dosage, post-RFA VAS score decreased by not less than 2 but by < 5 compared to before RFA) in 3 (9.1%), and poor in 10 patients (30.3%). Thus, the response rate was 69.7%. Conclusion: RFA is a safe and effective method for treating painful metastatic bone tumors.