Combined Ablation and Radiation Therapy of Spinal Metastases: A Novel Multimodality Treatment Approach

Abstract

Background: Radiation therapy (RT) is the current gold standard for palliation of painful vertebral metastases. However, other percutaneous modalities such as radiofrequency ablation (RFA), cryoablation, and vertebral augmentation have also been shown to be effective in alleviating symptoms. Combined RT and ablation may be more effective than either therapy alone in palliating painful metastatic disease to the spine. Objective: To evaluate the safety and efficacy of combined ablation, either RFA or cryoablation, and RT in the treatment of spinal metastases. Study Design: Retrospective study. Setting: This is a retrospective study at a single institution. Methods: Medical records of all patients who underwent ablation of spine lesions at a single institution between March 2012 and June 2014 were reviewed; patients treated with both RT and either RFA or cryoablation concurrently were identified. Pain scores before and after RFA were measured with the numerical rating scale (NRS) (0 – 10 point scale) and compared. Procedural complications, changes in general activity level, and pain medication usage after ablation were also recorded. When available, follow-up imaging was evaluated for evidence of residual or recurrent disease. Results: Twenty-one patients with 36 spine metastases were treated with RT and percutaneous ablation concurrently; either RFA (21/22) or cryoablation (1/22). One patient received 2 separate RFA treatments. Overall, mean worst pain score (8.0, SD = 2.3) significantly decreased at both one week (4.3, SD = 3.1; P < .02) and 4 weeks (2.9, SD = 3.3; P < .0003). Temporary postprocedural radicular pain occurred after one RFA treatment (4.5%; 1/22). Seven patients had radiation resistant tumors (renal cell, melanoma, or sarcoma). Post-procedural imaging (median 6 months; range 2 – 27 months) showed stable treated disease in 12/13 treatments at 3 months and 10/10 at 6 months. Limitations: The therapeutic effect of vertebral augmentation versus percutaneous ablation cannot be separated in this retrospective study. Radiation treatment protocols were variable and included both stereotactic body and conventional RT which may have different safety and efficacy profiles. Conclusion: Percutaneous ablation and concurrent RT is safe and effective in palliating painful spinal metastases and can be effective in those who have radiation resistant tumor histology. Key words: Interventional spine oncology, pain, percuataneous ablation, radiofrequency ablation, cryoablation, radiation therapy, spine metastases, vertebroplasty