Microwave Ablation as a Treatment for Spinal Metastatic Tumors: A Systematic Review

Background: Microwave ablation (MWA) is a novel technique that offers several potential advantages over existing ablation systems, which include production of larger ablation zones, shorter procedural times, and more effective heating through high impedance tissues such as bone. Methods: A systematic review was performed using inclusion criteria defined as follows: 1) metastatic spinal tumors treated with open or percutaneous MWA alone or in combination with other treatments, 2) available data on pain palliation and/or local tumor control, and 3) retrospective or prospective studies with at least 1 patient. Results: A total of 156 patients harboring 196 spinal lesions underwent MWA in the 8 included studies. Most studies employed the use of additional interventions, which included minimally invasive open surgery with pedicle screw fixation, traditional open surgical intervention, and cement augmentation. Despite the variability in time intervals for pain assessment, postoperative pain scores decreased considerably in both percutaneous and open MWA studies. No evidence of tumor progression was additionally seen in >80% of patients at the last follow-up across 5 studies. Complications were reported in 6.5% of all patients who underwent percutaneous MWA and in 12.2% of patients who underwent open MWA. Conclusions: This review showed that MWA can be effective in achieving analgesia for up to 6 months in select cases, although most procedures were performed in combination with augmentation and/or open surgery. Local tumor control was additionally successful in most patients, suggestive of a potential curative role for MWA.