Local Control and Vertebral Compression Fractures After Stereotactic Body Radiotherapy for Spinal Metastases

Objectives: This study aimed to evaluate the efficacy and toxicity of stereotactic body radiotherapy (SBRT) for spinal metastases, focusing on pain control, local tumor control, and the incidence of vertebral compression fractures (VCF). Materials and Methods: We retrospectively analyzed 179 patients with 217 spinal metastatic lesions who underwent SBRT between July 2020 and April 2022. The prescribed doses for SBRT were 18 or 20 Gy for one fraction, ≥24 Gy for three fractions, ≥20 Gy for four fractions, and ≥25 Gy for five fractions. Patient-reported treatment response was evaluated 1-3 months after SBRT completion. Local recurrence was defined as failure within the radiotherapy field. Pain response, local progression-free survival (LPFS), and the incidence of painful VCF were assessed. Prognostic factors for LPFS and VCF risk factors were evaluated. Results: The overall pain response rate was 80.8%. LPFS rates were 90.6% at 1 year and 83.0% at 2 years. Lytic/mixed lesions and involvement of multiple segments were significant prognostic factors for reduced LPFS. The cumulative incidence of painful VCF was 8.7% at 1 year and 12.8% at 2 years. A biologically effective dose (BED₃) ≥104 Gy was the only significant risk factor for painful VCF. Conclusions: SBRT demonstrated high efficacy for pain and local tumor control in spinal metastases, with an acceptable VCF risk.