O09 * CLINICAL OUTCOME OF 50 CHILDREN WITH INTRACRANIAL EPENDYMOMA TREATED WITH PENCIL BEAM SCANNING PROTON THERAPY

Abstract

INTRODUCTION: To assess the clinical outcome of pencil beam scanning proton therapy (PT) for the treatment of pediatric patients with intracranial ependymoma. METHOD: Between July 2004 and March 2013, 50 patients (median age, 2.6 years) with WHO Grade 2-4 intracranial ependymoma (infratentorial; 36/50) received adjuvant local irradiation only with PT at Paul Scherrer Institute. Seventeen (34%) patients presented with macroscopic residual disease after subtotal resection before starting PT (8 with residual tumor ≤ 1.5 cc and 9 with residual tumor >1.5 cc). Median prescribed dose was 59.4 Gy(RBE) (range, 54 - 60). RESULTS: With a mean follow-up time of 43.4 months (range, 8.5 -113.7) seven (14%) patients experienced local failure, 6 of them with infratentorial tumors and one with supratentorial tumors; 4 of the local failures were in patients presenting with residual disease ≥ 1.5 cc at the time of PT and 3 without residual macroscopic disease. One patient with local, infratentorial, tumor control developed supratentorial metastasis. Two patients with local failure developed microscopic dissemination at the time of the local failure with positive malignant cells into the CSF. Five patients died from tumor progression. Actuarial 5-year local control rates were 78 ± 7.5% and 5-year overall survival rates were 84 ± 6.8%. Three patients developed grade ≥ 3 toxicity (unilateral deafness in patients with infratentorial tumors; n = 2; fatal brainstem necrosis; n = 1). CONCLUSION: Local control and survival rates after PT for young ependymoma patients are excellent considering the high grade histology in 92% of the patients and the number of patients with residual tumor ≥ 1.5 cc.