Primary results of proton radiotherapy for 26 meningioma patients

Objective: To investigate the safety and efficacy of proton beam radiation therapy (PBRT) in patients with World Health Organization (WHO) Grade I/II meningioma. Methods: Twenty-six patients with intracranial (n = 8, 30.8%) or skull-base (n = 18, 69.2%) meningioma treated with PBRT from May 2015 to October 2018 were analyzed retrospectively. The median age of the cohort was 42 years (range 15-79 years). Eight patients had WHO Grade I meningioma, and 9 had WHO Grade II meningioma, respectively. Nine patients had clinical (radiological) diagnosis without histology. Seven patients received post-surgical PBRT (2 patients underwent Simpson I-III resection, 5 patients underwent Simpson IV-V resection); 10 patients were irradiated for local recurrence after initial surgical resection. Results: All patients completed planned PBRT without break, and the median dose was 54 Gray-Equivalent (GyE) (range 50.4-60 GyE, 1.8-2 GyE/daily fraction). With a median follow-up of 22.2 (range 1.6-36.4) months, the 2-year overall survival and progression-free survival rates were both 100%. Grade I skin erythema and alopecia were observed in 22 patients and Grade I mucositis was observed in 2 patients. No acute of late toxicities of Grade 2 or above was observed. Conclusions: PBRT appeared to be a favorable treatment option for intracranial and skull base meningioma. Treatment-induced adverse effects and early response to PBRT were both highly acceptable. Longer follow-up is needed to evaluate the long-term outcome in terms of disease control, survival, as well as potential late effects. (authors)