Targeted radiofrequency ablation of metastatic posterior vertebral body lesions in patients with soft tissue sarcomas.

Abstract

10585 Background: Metastatic spinal lesions can be debilitating with significant impact on patients quality of life. Concern for damage to adjacent neural elements during treatment exist due to high radiation doses required to treat certain radioresistant spinal lesions such as soft tissue sarcoma. Radiofrequency ablation (RFA) of metastatic lesions has been shown to be effective in bone. Spine anatomy presents challenges for minimally invasive (MI) treatment of posterior vertebral body lesions. Targeted RFA (t-RFA) using a novel tumor ablation system, designed for spinal anatomy is evaluated in patients with symptomatic posterior vertebral wall spinal lesions. Methods: Five patients with metastatic leiomyosarcoma or liposarcoma and posterior vertebral body spine lesions, treated by prior radiation with continued progression of lesion size and pain received t-RFA, using a novel spinal tumor ablation system (STAR, DFINE), which contains an articulating bipolar, extensible electrode for navigation. Device thermocouples (TC) permit real time monitoring of the ablation zones to determine size. Sequential post-procedural pain scores, PET and contrast enhanced magnetic resonance imaging, and histopathology of treated area was performed. Results: No complications or thermal injury occurred. Intra-procedural imaging demonstrated the articulated, bipolar instrument was able to navigate to posterior lesions. Post-ablation MRI demonstrated lesion necrosis within a discrete ablation zone. No evidence of malignancy by PET or histopathology was noted through 10 months. All patients reported post procedural pain relief. Systemic therapy was not interrupted. Conclusions: Navigational t-RFA proved a safe and effective, non-ionizing palliative therapy alternative for radio-resistant lesions . Post-ablation imaging and histology confirmed metastatic lesions were necrotic and included in ablation zone with tumor control 10 mos post treatment. Ablation zone was very consistent with real time temperature readings. t-RFA permitted MI targeted treatment of lesions within close proximity of spinal cord, not controlled by systemic therapy. Prospective clinical trial is under preparation.