Radiofrequency Ablation for the Treatment of Metastatic Spinal Tumors
Guest blog post by Aldo Gonzalez-Beicos, MD
From the University of Miami Health System Sylvester Comprehensive Cancer Center
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The number of patients living with cancer in the United States is estimated to be 4.86 million.1 At least 30% to 40% of cancer patients will present with complaints related to metastatic spinal tumors, often involving several levels of the spine. Tumors that involve the spine may cause intolerable pain by a number of different mechanisms. As the tumor grows within the vertebral body the pressure upon the endosteum increases and an inflammatory reaction of the periostium ensues. At the tumor-bone interphase there is release of chemical mediators that facilitate nociceptive impulses. As the tumor extends beyond the confines of the vertebral body, it can impinge upon exiting nerve roots causing radicular pain. While the tumor continues to grow and the vertebral body weakens, axial loading of the spine can result in pathologic compression fractures, resulting in pain.
The standard treatment of metastatic osseous lesions to the spine relies on the optimization of chemotherapy, decreasing bone resorption (bisphosphonates) and administering fractionated radiation to the involve segment of the spine. If cord compression or spinal instability occurs in the setting of a pathologic compression fracture, surgical decompression and stabilization is the treatment of choice. Pathologic compression fractures of the spine not associated with instability may be treated with percutaneous therapies like vertebroplasty or kyphoplasty.
Over the last decade, the effectiveness of radiofrequency ablation in reducing pain associated with benign osseous tumors as well as bone metastasis has been documented. Radiofrequency ablation (RFA) is gaining momentum as a palliative therapy for painful spinal metastasis when standard therapies are contraindicated or have failed to control symptoms.2 The idea behind the procedure is to address the mass-related pain generators by ablating the tumor and at the same time providing access for cement implantation into the weakened and often fractured vertebral body. This is in contrast to the more routinely utilized vertebral augmentation procedures like vertebroplasty or kyphoplasty, were only cement is implanted to correct the instability associated with a pathologic fracture without ablating the tumor. The STAR RF ablation system (DFINE) has been designed specifically to navigate the spine and facilitate RF probe placement into the vertebral body (read a case report from the February issue in which the STAR system is used for a vertebral metastasis). The tip of the bipolar RF probe is able to articulate allowing placement into almost any part of the vertebral body via a single transpedicular approach. Thermocouples proximal to the active tip allow for constant monitoring of the temperature at the periphery of the ablation zone, which is a key feature when performing ablations near vital structures like the spinal cord. Typically, this procedure can be performed in the outpatient setting under local anesthesia and moderate sedation. Recently, the results of a multicenter retrospective review of 92 patients who underwent RFA using the STAR RF for painful metastatic osseous lesions to the spine showed that the procedure is safe and significantly reduced pain up to 6 months post-operatively.3
In conclusion, RFA for spinal metastatic lesions seems to be a safe and effective procedure with the potential to have a huge impact for patients that are suffering with intractable pain and have run out of treatment options. Several prospective and comparative studies that are currently underway will shed some light on whether this treatment could be considered a first-line option in the near future.
References
1. Howlader N, Noone AM, Krapcho M, et al (eds). SEER Cancer Statistics Review, 1975-2009 (Vintage 2009 Populations), National Cancer Institute. Bethesda, MD, https://seer.cancer.gov/csr/1975_2009_pops09/, based on November 2011 SEER data submission, posted to the SEER web site, April 2012.
2. Goetz MP, Callstrom MR, Charboneau JW, et al. Percutaneous image-guided radiofrequency ablation of painful metastases involving bone: a multicenter study. J Clin Oncol. 2004;22(2):300-306.
3. Anchala PR, Irving WD, Hillen TJ, et al. Treatment of metastatic spinal lesions with a navigational bipolar radiofrequency ablation device: a multicenter retrospective study. Pain Physician. 2014;17(4):317-327.
