Stereotactic Radiosurgery for the Treatment of Primary and Metastatic Spinal Sarcomas

Purpose: Despite advancements in local and systemic therapy, metastasis remains common in the natural history of sarcomas. Unfortunately, such metastases are the most significant source of morbidity and mortality in this heterogeneous disease. As a classically radioresistant histology, stereotactic radiosurgery has emerged to control spinal sarcomas and provide palliation. However, there is a lack of data regarding pain relief and relapse following stereotactic radiosurgery. Methods: We queried a retrospective institutional database of patients who underwent spine stereotactic radiosurgery for primary and metastatic sarcomas. The primary outcome was pain relief following stereotactic radiosurgery. Secondary outcomes included progression of pain, radiographic failure, and development of toxicities following treatment. Results: Forty treatment sites were eligible for inclusion; the median prescription dose was 16 Gy in a single fraction. Median time to radiographic failure was 14 months. At 6 and 12 months, radiographic control was 63% and 51%, respectively. Among patients presenting with pain, median time to pain relief was 1 month. Actuarial pain relief at 6 months was 82%. Median time to pain progression was 10 months; at 12 months, actuarial pain progression was 51%. Following multivariate analysis, presence of neurologic deficit at consult (hazard ratio: 2.48, P <.01) and presence of extraspinal bone metastases (hazard ratio: 2.83, P <.01) were associated with pain relief. Greater pain at consult (hazard ratio: 1.92, P <.01), prior radiotherapy (hazard ratio: 4.65, P =.02), and greater number of irradiated vertebral levels were associated with pain progression. Conclusions: Local treatment of spinal sarcomas has remained a challenge for decades, with poor rates of local control and limited pain relief following conventional radiotherapy. In this series, pain relief was achieved in 82% of treatments at 6 months, with half of patients experiencing pain progression by 12 months. Given minimal toxicity and suboptimal pain control at 12 months, dose escalation beyond 16 Gy is warranted.