Proton therapy re-irradiation provides promising clinical results in recurrent brain meningioma

Abstract

Purpose To evaluate the clinical outcomes, toxicity and prognostic factors conditioning survival of reirradiation with Proton therapy for recurrent meningiomas. Methods Recurrent meningioma who failed after radiotherapy were re-irradiated with active scanning proton therapy with a median dose of 54 GyRBE (range 50.4-60 GyRBE). Progression-free survival (PFS) and overall survival (OS) were estimated using the Kaplan-Meier method. The log rank test was performed to compare the entire survival experience between groups (significant p-value ≤ 0.05). Associations between qualitative variables were analyzed with the Fisher exact test (significant p-value ≤ 0.05). Results Thirty-two patients were re-irradiated with Proton therapy (10 grade I, 22 grade II-III). Median tumor volume at the time of re-irradiation was 43 cc (range 1.2-225.5) and median time from prior RT to reirradiation was 66 months (range 4-288). At a median follow-up of 27 months, 1-yr and 2-yr PFS were 89.4% and 74.5% (1-yr and 2-yr PFS were 100% for grade I, 100% and 76% for grade II, 66% and 50% for grade III). 1-yr and 2-yr OS were 86.6% and 83.0% (2-yr OS were 87% for grade I, 86% for grade II, 66% for grade III). Local recurrence rate was 34% with a median time of recurrence of 13.4 months. Five patients (14%) developed radionecrosis with a median time of 3.4 months from the end of PT (range 3-8.8). Conclusions Re-irradiation with proton therapy seems to be a safe and effective treatment in patients with recurrent meningioma, also for large volume and aggressive lesions (grade II-III).