Treatment of metastatic spinal lesions with a navigational bipolar radiofrequency ablation device: A multicenter retrospective study

Background: Spinal metastatic lesions are a common occurrence among oncology patients and contribute to significant morbidity. Treatment options have been limited in their effectiveness and scope to this point. Objective: This study aims to report the safety and efficacy of radiofrequency ablation (RFA) of malignant spinal lesions using a novel RFA bipolar tumor ablation system which includes a navigational electrode containing 2 active thermocouples. Study Design: IRB approved multicenter retrospective review of patients receiving RFA as a treatment of metastatic osseous lesions between March 2012 and March 2013. Setting: This study consists of patients from 5 large academic centers. Method: One hundred twenty-eight metastatic lesions were identified in 92 patients who underwent a total of 96 procedures. Cement augmentation was performed when the vertebral body was at risk or had a pathological fracture. Visual analogue scale (VAS) scores were obtained preoperatively as well as postoperatively at the one week, one month, and 6 month time points. Interval change in the patients' pain medications was recorded. Postoperative imaging was used to assess tumor burden at the treated level when available. Results: RFA was technically successful in all of the lesions without complication or thermal injury. Our study demonstrated significant (P < 0.01) decreases in the VAS scores at one week, one month, and 6 months postoperatively. In our largest center, 54% of our patients experienced a decrease and 30% had no change in their pain medications postoperatively. Sixtytwo percent of the spinal lesions in this largest institution were located in the posterior vertebral body. Post-ablation imaging confirmed size of ablation zones consistent with that measured by the thermocouples. Limitations: The main limitations of this study are the heterogeneous patient population, data set, and potential confounding variable of concurrent cement augmentation. Conclusion: The STAR System is an RFA device that was safely and effectively used in the treatment of spine metastatic osseous lesions. This new device allows RFA treatment of previously untreatable lesions with resultant reduction in pain that was not controlled by systemic or radiation therapy.