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

Introduction: Only a small percentage of meningiomas are spinal. 5% of SMs have WHO grades 2 and 3 characteristics, albeit they are usually benign. High-grade SMs have poor postoperative results, hence adjuvant treatment, notably radiotherapy, is being considered to increase tumor control and survival. These tumors are poorly investigated, and adjuvant radiation is contentious. We wanted to analyze the demographics of this unusual tumor and the outcomes of surgery with adjuvant therapy versus 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. Kaplan-Meier survival analysis was conducted to study overall survival. All analyses were performed on R.

Results: Using the NCDB database, 13,184 SM patients were found, with only 669 (5%) having high-grade SMs. High-grade SM patients had a younger median age (57 years (IQR: 44-68) vs. 65 years (54-75); p< 0.001). Compared to the low-grade cohort, the high-grade cohort had a considerably higher male representation (33% vs. 20%; p< 0.001). After 1:1 propensity-score matching, all baseline patient characteristics were balanced (p≥0.05) between groups. Median time from diagnosis to radiotherapy was 64.0 days (43.0-109.0), and radiotherapy was 39.0 days (36.0-43.0). Most (93%), had external beam radiation, and the rest received stereotactic radiosurgery. The median dose was 5,040 cGy (4,500-5,400). The average follow-up was 60.5(36-89) months. Before matching, patients who received both surgery and radiotherapy had worse overall survival outcomes than those who just received surgery (p=0.001). After propensity-score matching, overall survival remained unchanged (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.