Radiographic Local Control of Spinal Metastases with Percutaneous Radiofrequency Ablation and Vertebral Augmentation

BACKGROUND AND PURPOSE:Combination radiofrequency ablation and vertebral augmentation is an emerging minimally invasive therapy for patients with metastatic spine disease who have not responded to or have contraindications to radiation therapy. The purpose of this study was to evaluate the rate of radiographic local control of spinal metastases treated with combination radiofrequency ablation and vertebral augmentation.MATERIALS AND METHODS:We retrospectively reviewed our tumor ablation database for all patients who underwent radiofrequency ablation and vertebral augmentation of spinal metastases between April 2012 and July 2014. Tumors treated in conjunction with radiation therapy were excluded. Tumor characteristics, procedural details, and complications were recorded. Posttreatment imaging was reviewed for radiographic evidence of tumor progression.RESULTS:Fifty-five tumors met study inclusion criteria. Radiographic local tumor control rates were 89% (41/46) at 3 months, 74% (26/35) at 6 months, and 70% (21/30) at 1 year after treatment. Clinical follow-up was available in 93% (51/55) of cases. The median duration of clinical follow-up was 34 weeks (interquartile range, 15–89 weeks), during which no complications were reported and no patients had clinical evidence of metastatic spinal cord compression at the treated levels.CONCLUSIONS:Combination radiofrequency ablation and vertebral augmentation appears to be an effective treatment for achieving local control of spinal metastases. A prospective clinical trial is now needed to replicate these results.

Metastatic spine disease affects 5%–10% of patients with cancer.¹ Approximately 90% of symptomatic patients present with pain, which is most commonly due to biochemical stimulation of endosteal nociceptors, tumor mass effect, and/or associated pathologic fracture.² These patients are also at risk for metastatic spinal cord compression, which occurs in 10%–20% of patients and is most often due to posterior extension of vertebral body tumor.^3,4 The resulting pain and neurologic deficits are associated with decreased quality of life and shortened life expectancy.⁵ Therefore, the goals of treatment are both pain palliation and local tumor control.Radiation therapy is the standard of care for pain palliation and local control of spinal metastases, but it has several important limitations. First, certain tumor histologies respond less favorably to radiation therapy, particularly non-small cell lung cancer, renal cell carcinoma, melanoma, and sarcoma.⁶ Second, radiation therapy of spinal metastases is limited by the cumulative tolerance of the spinal cord, which often precludes retreatment of recurrent disease or progressive disease at adjacent vertebral levels.⁷ Third, radiation therapy excludes patients from certain systemic chemotherapy clinical trials.Combination radiofrequency ablation (RFA) and vertebral augmentation is an emerging minimally invasive therapy for patients with metastatic spine disease who have not responded to or have contraindications to radiation therapy. An ablation probe is percutaneously placed into the tumor, and high-frequency alternating current is passed through an electrode at the probe tip, generating frictional heating and necrosis of adjacent tissue.⁸ Cement is then instilled through the same percutaneous cannula to stabilize or prevent associated pathologic fracture.^9,10 The tandem procedure can be performed in an outpatient setting with the patient under conscious sedation, requires minimal recovery, and does not hinder or delay adjuvant therapies such as radiation or systemic chemotherapy. Multiple case series have shown decreased pain scores after RFA and vertebral augmentation of spinal metastases,^11–15 but evidence that percutaneous therapy achieves local tumor control is limited to case reports and small case series without internal controls.^13,14 The purpose of this study was to retrospectively evaluate the rate of radiographic local control of spinal metastases treated with combination RFA and vertebral augmentation at a National Cancer Institute–Designated Cancer Center.