RONC-24. PROTON THERAPY FOR PEDIATRIC EPENDYMOMA: MATURE OUTCOMES FROM THE UNIVERSITY OF FLORIDA AND MASSACHUSETTS GENERAL HOSPITAL

Abstract

OBJECTIVEReport long-term efficacy and toxicity of proton therapy for pediatric ependymoma.MATERIALS AND METHODSBetween 2000–2017, 318 children with nonmetastatic grade II/III intracranial ependymoma received proton therapy at Massachusetts General Hospital and the University of Florida. Median age was 3.5 years (range, 0.7–21.3 years); 56% were male. Most (69%) tumors were in the posterior fossa and classified as WHO grade III (64%). Eighty-four percent had a gross total or near total tumor resection before radiotherapy and 30% received chemotherapy. Median radiation dose was 55.8 CGE (range, 50.4–59.4 CGE).RESULTSMedian follow-up was 6 years (range, 0.6–19.2 years). Seven-year local control, progression-free survival, and overall survival rates were 77.1% (95% CI 71.7–81.7%), 64.4% (95% CI 58.6–69.8%), and 82% (76.9–86.2%), respectively. Subtotal resection was associated with inferior local control (60% vs 80%; p<0.01), progression-free survival (49% vs 67%; p<0.01), and overall survival (69% vs 84%; p<0.05). Male gender was associated with inferior progression-free (59% vs 71%; p<0.01) and overall survival (77% vs 89%; p<0.05). Twenty patients (6.2%) require hearing aids; of these, 12/20 received cisplatin. Grade 3+ brainstem toxicity rate was 1.6% and more common in patients who received >54 CGE. The rate of second malignancy was 0.9%.CONCLUSIONProton therapy offers commensurate disease control to modern photon therapy without unexpected toxicity. The high rate of long-term survival justifies efforts to reduce radiation exposure in this young population with brain tumors. Independent of modality, this large series confirms extent of resection as the most important modifiable factor for survival.