Outcomes of Radiotherapy for WHO Grade 2 Meningioma: Survival, Local Control, and Prognostic Factors

Background and Objectives: The optimal role of postoperative radiotherapy and the prognostic factors influencing outcomes in patients with WHO grade 2 meningioma remain controversial. This study evaluated survival outcomes, local control, treatment-related toxicity, and prognostic factors in patients treated with postoperative radiotherapy. Materials and Methods: This retrospective single-center study included 50 consecutive adult patients with histologically confirmed WHO grade 2 meningioma who underwent surgical resection followed by radiotherapy between 2013 and 2024. Overall survival (OS) and local control (LC) were estimated using the Kaplan-Meier method, and median follow-up was calculated using the reverse Kaplan-Meier method. Univariable and multivariable Cox proportional hazards regression analyses were performed to identify prognostic factors associated with OS, while univariable analyses were performed for LC. Results: The reverse Kaplan-Meier median follow-up was 20.9 months (95% CI, 13.2-34.8). During follow-up, 10 patients died and 7 developed local recurrence. Median OS was 59.3 months (95% CI, 49.9 months-not estimable). The estimated 2- and 5-year OS rates were 85.0% and 44.8%, respectively, while the corresponding LC rates were both 76.2%. Increasing age and larger tumor size were independently associated with worse OS. All deaths and all local recurrences occurred in patients with postoperative residual disease. Acute adverse events were limited to Grade 1-2 toxicity, and no Grade ≥3 acute or late toxicities were observed. Conclusions: Postoperative radiotherapy achieved favorable local control with an acceptable safety profile in patients with WHO grade 2 meningioma. Postoperative residual disease was strongly associated with adverse clinical outcomes, while increasing age and larger tumor size were independently associated with worse overall survival. These findings support the importance of maximal safe resection, careful postoperative risk stratification, and individualized multidisciplinary treatment planning.