Supplemental Material for:Underutilization of Adjuvant Radiation in Malignant Meningioma:

Using the Surveillance, Epidemiology, and End Results (SEER) database (2000-2022), we identified 1,803 patients with malignant meningioma not otherwise specified (ICD-O-3 9530/3). A sensitivity analysis including all histologic subtypes was also performed (n=1,989). Analyses of radiation receipt were restricted to surgically treated patients (n=1,338), while survival analyses were conducted in the full cohort.

Multivariable logistic regression identified predictors of radiation receipt, and overall survival was evaluated using stratified Cox regression. Models adjusted for race, sex, age, income category, rural-urban designation, and year of diagnosis. Results Among 1,338 surgically treated patients, 40.3% received postoperative radiation.

Radiation utilization increased from 24.3% in 2000-2004 to 50.5% in 2020-2022 (OR 1.06/year, 95% CI 1.04-1.08, p<0.001). Patients in the highest income category were more likely to receive radiation than those in the lowest category (46.7% vs 28.9%; OR 2.00, 95% CI 1.07-3.81, p=0.032). Race was not independently associated with radiation receipt.

Radiation utilization was similar among patients younger than 70 years and those aged 70 years or older (40.5% vs 39.9%; p=0.89). Conclusion Postoperative radiation therapy was underutilized among surgically treated patients with malignant meningioma, although utilization increased over time. Higher income was independently associated with receipt of adjuvant radiation, suggesting socioeconomic factors may contribute to treatment variation in this population.</p>