Purpose Stereotactic body radiation therapy (SBRT) is a common treatment option for patients with metastatic tumors of the spine. The optimal treatment-, tumor-, and patient-specific characteristics necessary to achieve durable outcomes remain less well understood given the heterogeneous nature of the patient population this modality typically serves. The objective of this analysis was to better understand the determinants underlying SBRT spine treatment outcomes. Methods and Materials A total of 127 patients with 287 spine tumors were treated between March 2010 and May 2015. The median total doses for single-fraction and hypofractionated courses of treatment were 16 Gy (range, 16-20 Gy) and 24 Gy (range, 16-40 Gy), respectively. Radiologic local control and numeric pain score data were measured, and univariate and multivariate analyses were done to determine factors predictive of treatment response. Results Median follow-up was 5.9 months (range, 1-61 months). Radiologic local control was achieved in 84.7% of patients at 6 months and in 74.7% of patients at 1 year. Local control was found to be affected by the Spinal Instability Neoplastic Score, and was worse in patients with scores ≥7 (hazard ratio [HR]: 4.25; 95% confidence interval [CI], 1.57-11.51). Patients who required upfront surgical intervention to alleviate spinal cord compression, address mechanical spinal instability, or both had worse local control than those who did not require surgery (HR: 2.32; 95% CI, 1.04-5.17). Patients treated with a hypofractionated course compared with a single fraction had worse radiologic local control (HR: 2.63; 95% CI, 1.27-5.45). No patients developed radiation-induced myelitis after treatment, and the vertebral compression fracture rate was 9.1% after SBRT. Conclusions Patients with potentially unstable spines or needing upfront spinal surgery before SBRT are less likely to achieve durable radiologic local control. Additionally, patients treated with single-fraction regimens have improved local control compared with those treated with hypofractionated radiation.

The purpose of our study is to evaluate the outcomes of patients with high-grade epidural spinal cord compression (ESCC) spinal metastases treated with spine stereotactic radiosurgery (SSRS) in the postoperative setting. Materials/Methods: We reviewed the medical records of 20 patients with high-grade (ESCC) spinal metastases who underwent separation surgery followed by postoperative spine stereotactic radiosurgery (SSRS). CT simulation and postoperative myelography were fused to delineate planning target volume (PTV), spinal cord and dural margins. Six patients (30%) received a single fraction of 16 Gy, and 14 patients (70%) received 24-27 Gy in 3 fractions. Preoperative epidural spinal cord compression (Bilsky) scores of 1c, 2, and 3 were found in 30%, 50% and 20% of patients, respectively. Patients were followed with spinal MRI and CTmylography at regular intervals to determine local control (LC). Pain control data were collected to determine clinical treatment response. Radiographic local control was calculated using the Kaplan-Meier method. Results: Fifty-three segments were treated. The median PTV was 88.0 cm 3 (range: 24.6e354.6 cm 3), with a median V90 of 94% and D90 of 93%. Solid tumor histology represented 80% of the patient population. Four patients (20%) had been treated with radiation to the spine utilizing conventional fractionation prior to surgical intervention. The median followup for this cohort was 9.5 months (range: 2-31mo). The 1-year radiographic LC was 75.3%. Durable pain control, defined as a numeric pain score of <4 out of 10, was achieved in 73% of patients. Four patients failed locally. Two of these patients were salvaged with additional SBRT and now have stable disease. No grade-2 or higher treatment-related toxicity has been observed. Conclusion: The combination of separation surgery with stereotactic spine radiosurgery can offer patients with high-grade epidural spinal cord compression spinal metastases the chance of effective palliation, along with durable tumor control. Separation surgery may optimize the conditions for the safe and effective delivery of spine radiosurgery.