High-grade spinal meningiomas and adjuvant radiotherapy: a propensity score matched analysis

Introduction: Spinal meningiomas (SMs) constitute a minority of all meningiomas. Although typically benign, 5% of SMs present with higher-grade features (WHO grades 2 and 3). Given the poor postoperative outcomes of high-grade SMs, there is growing interest in adjuvant treatment modalities, especially radiotherapy, to enhance tumor control and improve overall survival. We aimed to study the demographic characteristics of this rare tumor and investigate the outcomes associated with the use of surgery with adjuvant therapy in contrast to surgery alone.

Methods: The National Cancer Database (NCDB) was queried for patients with spinal meningiomas from 2004 to 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.

Results: A total of 13,184 patients diagnosed with SMs were identified using the NCDB database, of whom only a minority (n=669; 5%) had high-grade SMs. Patients with high-grade SMs presented at a younger median age (57 years (IQR: 44-68) vs. 65 years (54-75); p< 0.001). Males were significantly overrepresented among the high-grade cohort, as compared to the low grade one (33% vs. 20%; p< 0.001). After propensity-score 1:1 matching, a balanced distribution (p≥0.05) across all baseline patient characteristics was achieved between the groups. The median duration from diagnosis to the start of radiotherapy was 64.0 days (43.0-109.0), while the median duration of radiotherapy was 39.0 days (36.0-43.0). The vast majority (93%), underwent external beam radiation, and the remainder received stereotactic radiosurgery (SRS). The median total dose administered was 5,040 cGy (4,500-5,400). Patients were followed for an average of 60.5(36-89) months. Prior to matching, survival analysis revealed significantly worse overall survival outcomes associated with patients undergoing both surgery and radiotherapy as compared to those only receiving surgery (p=0.001). However, after propensity-score matching, no difference in overall survival was observed (p=0.19)

Conclusion : This study reveals major demographic differences between high- and low-grade SMs. There was a marked overrepresentation of younger and male patients among high-grade SMs. However, due to confounding, OS outcomes between patients receiving surgery alone and those receiving surgery with adjuvant radiotherapy are not causally interpretable.