BACKGROUND: Vertebral compression fracture (VCF) is a challenging and not infrequent complication observed following spine stereotactic body radiation therapy (SBRT). OBJECTIVE: To summarize the data from the multiple studies that have been published, addressing the risk and predictive factors for VCF post-SBRT. METHODS: A systematic literature review was conducted. Studies were selected if they specifically addressed risk factors for post-SBRT VCF in their analyses. RESULTS: A total of 11 studies were identified, reporting both the risk of VCF post-SBRT and an analysis of risk factors based on univariate and multivariate analysis. A total of 2911 spinal segments were treated with a crude VCF rate of 13.9%. The most frequently identified risk factors on multivariate analysis were: lytic disease (hazard ratio [HR] range, 2.76-12.2), baseline VCF prior to SBRT (HR range, 1.69-9.25), higher dose per fraction SBRT (HR range, 5.03-6.82), spinal deformity (HR range, 2.99-11.1), older age (HR range, 2.15-5.67), and more than 40% to 50% of vertebral body involved by tumor (HR range, 3.9-4.46). In the 9 studies that specifically reported on the use of post-SBRT surgical procedures, 37% of VCF had undergone an intervention (range, 11%-60%). CONCLUSION: VCF is an important adverse effect following SBRT. Risk factors have been identified to guide the selection of high-risk patients. Evidence-based algorithms with respect to patient selection and intervention are needed.

We report mature outcomes for a cohort of patients with no prior radiation (de novo) to the spine treated with 24 Gy in 2 daily fractions for metastases, which represents the same stereotactic body radiation therapy (SBRT) regimen under evaluation in the current Symptom Control-24 phase 3 randomized trial (NCT02512965). The cohort consisted of 279 de novo spinal metastases in 145 consecutive patients treated with 24 Gy in 2 SBRT fractions, identified from a prospective single-institution database. The endpoints were overall survival (OS), imaging-based local failure (LF), and cumulative risk of vertebral compression fractures (VCF). The median follow-up per treated metastasis was 15.0 months (range, 0.1-71.6). The 1-year and 2-year OS rates were 73.1% and 60.7%, respectively. Presence of epidural disease (P < .0001), lung (P = .0415), and renal cell (P < .0001) primary histologies and baseline diffuse metastases (P = .0034) were significant prognostic factors for OS. The 1-year and 2-year LF rates were 9.7% and 17.6%, respectively, and the median time to LF was 9.2 month (range, 0.4-31.3 months). Only the presence of epidural disease predicted for LF (P < .0001). The cumulative risk of VCF at 1 and 2 years was 8.5% and 13.8%, respectively. Lytic (P = .0143) or mixed lytic/blastic (P = .0214) lesions, spinal malalignment (P = .0121), and the dose to 90% of the planning target volume (P = .0085) were significant predictors for VCF. Twenty-four Gray in 2 daily fractions is safe and effective in achieving high tumor control rates for de novo spinal metastases. These outcomes will serve as a benchmark for the ongoing Symptom Control-24 randomized trial comparing 24 Gy in 2 SBRT fractions to 20 Gy delivered in 5 daily conventional fractions.

Study Design: A broad narrative review. Objectives: The objective of this article is to provide a technical review of spine stereotactic body radiotherapy (SBRT) planning and delivery, indications for treatment, outcomes, complications, and the challenges of response assessment. The surgical approach to spinal metastases is discussed with an overview of emerging minimally invasive techniques. Methods: A comprehensive review of the literature was conducted on the techniques, outcomes, and developments in SBRT and surgery for spinal metastases. Results: The optimal management of patients with spinal metastases is complex and requires multidisciplinary assessment from an oncologic team that is familiar with the shifting paradigm as a consequence of evolving techniques in surgery and stereotactic radiation, as well as new developments in systemic agents. The Spinal Instability Neoplastic Score and the epidural spinal cord compression (Bilsky) grading system are useful tools that facilitate communication among oncologic team members and can direct management by providing a baseline assessment of risks prior to therapy. The combined multimodality approach with “separation surgery” followed by postoperative spine SBRT achieves thecal sac decompression, improves tumor control, and avoids complications that may be associated with more extensive surgery. Conclusion: Spine SBRT is a highly effective treatment that is capable of delivering ablative doses to the target while sparing the critical organs-at-risk, chiefly the critical neural tissues, within a short and manageable schedule. At the same time, surgery occupies an important role in select patients, particularly with the expanding availability and expertise in minimally invasive techniques. With rapid adoption of spine SBRT in centers outside of the academic setting, it is imperative for the practicing oncologist to understand the relevance and application of these evolving concepts.

The oligometastatic state is hypothesized to represent an intermediary state of cancer between widely metastatic disease and curable, localized disease. Advancements in radiotherapy have allowed for delivery of high precision, dose escalated treatment known as stereotactic body radiotherapy (SBRT) to targets throughout the body with excellent rates of local control. Recently, the first phase II randomized trial comparing conventional radiotherapy to comprehensive SBRT of oligometastatic disease demonstrated an overall survival and progression free survival advantage. The spine is a common site of metastasis, and a complex site for SBRT given the adjacent spinal cord and the tumor embedded within the bone tissue putting the patient at risk of fracture. Although there are expert spine SBRT guidelines for practice, there are as yet no reported randomized trials that proves superiority as compared to conventional radiation. The use of SBRT in patients with oligometastatic disease and spinal metastases is the focus of this review.