AbstractBackgroundThe aim of this study was to evaluate the efficacy of proton beam therapy for pediatric patients with ependymoma.MethodsProton beam therapy was conducted for six patients (three boys and three girls; age, 2–6 years; median, 5 years) with ependymoma. The tumors were WHO grades 2 and 3 in two and four patients, respectively. All patients underwent surgery (subtotal and gross total resection in three patients each) and proton beam therapy at doses of 50.4–61.2 GyE (median, 56.7 GyE). The mean doses to normal brain tissue in proton beam therapy and photon radiotherapy were simulated using the same treatment planning computed tomography images.ResultsAll patients completed the planned irradiation. The follow‐up period was 13–44 months (median, 24.5 months) from completion of proton beam therapy and all patients were alive at the end of this period. Local recurrence in the treatment field occurred in one patient at 4 months after proton beam therapy at 50.4 GyE. Alopecia and mild dermatitis occurred in all patients, but there was no severe toxicity. One patient had a once‐off seizure after proton beam therapy and alopecia persisted in another patient for 31 months, but no patients had difficulty with daily life. The simulation showed that proton beam therapy reduces the dose to normal brain tissue by approximately half compared with photon radiotherapy.ConclusionsProton beam therapy for pediatric ependymoma is safe, does not have specific toxicities, and can reduce irradiation of normal brain tissue.