408 High-Grade Spinal Meningiomas and Adjuvant Radiotherapy: A Propensity Score Matched Analysis

INTRODUCTION: Spinal meningiomas (SMs) are mostly benign, but 5% are higher-grade (WHO grades 2 and 3). Poor postoperative outcomes in high-grade SMs have spurred interest in adjuvant treatments like radiotherapy to improve survival. However, the role of radiotherapy remains controversial and understudied. METHODS: The National Cancer Database (NCDB) was queried for patients with spinal meningiomas from 2004- 2017. Basic statistics were used to identify differences between low- and high-grade tumors in terms of baseline characteristics. Surgery with and without adjuvant radiotherapy were compared after(1:1) propensity-score matching. Kaplan-Meier survival analysis was conducted to study overall survival. RESULTS: A total of 13,184 patients with SMs were identified from the NCDB database, with only 669 (5%) having high-grade SMs. High-grade SMs patients were younger (median age 57 vs. 65 years) and predominantly male (33% vs. 20%). After propensity-score 1:1 matching, baseline patient characteristics were balanced. The median time from diagnosis to radiotherapy was 64 days (43-109), and the median duration of radiotherapy was 39 days. Most patients (93%) received external beam radiation, with the remainder receiving stereotactic radiosurgery (SRS). The median total dose was 5,040 cGy (4,500-5,400). Patients were followed for an average of 60.5 months (36-89). Before matching, survival analysis showed worse overall survival for patients receiving both surgery and radiotherapy compared to surgery alone. After matching, no difference in overall survival was observed. CONCLUSIONS: This study reveals significant demographic differences between high- and low-grade SMs, with younger and male patients being overrepresented among high-grade SMs. No benefit from adjuvant radiotherapy was observed. However, due to confounding, overall survival outcomes between patients receiving surgery alone and those receiving surgery with adjuvant radiotherapy are not causally interpretable.