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

Introduction: Spinal meningiomas (SMs) are a small fraction of all meningiomas, with 5% being higher-grade (WHO grades 2 and 3). Due to poor postoperative outcomes of high-grade SMs, the interest in adjuvant treatments like radiotherapy is growing for better tumor control and survival. However, the understudied nature of these tumors and the unclear role of adjuvant radiotherapy make it a controversial management option. This study aims to analyze adjuvant therapy's demographic characteristics and outcomes post-surgery versus surgery alone for this rare tumor.

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 regarding baseline characteristics. Surgery with and without adjuvant radiotherapy was compared after (1:1) propensity-score matching. Kaplan-Meier survival analysis was conducted to study overall survival. All analyses were performed on R.

Results: A total of 13,184 patients diagnosed with SMs were identified using the NCDB database, of whom only a minority (5%) had high-grade SMs. Patients with high-grade SMs presented at a younger median age (p < 0.001). Males were significantly overrepresented among the high-grade cohort compared to the low-grade one (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 days, while the median duration of radiotherapy was 39 days. Most (93%) underwent external beam radiation; 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 months. Prior to matching, survival analysis revealed significantly worse overall survival outcomes associated with patients undergoing surgery and radiotherapy than 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. Additionally, no benefit associated with the use of adjuvant radiotherapy was discernible. However, due to confounding, overall-survival outcomes between patients receiving surgery alone and those receiving surgery with adjuvant radiotherapy are not causally interpretable.