Peer-reviewed article

RONC-05. Peri-transplant Radiation Therapy for Young Children Treated with High-Dose Chemotherapy for Primary Brain Tumors

· 1 Jun 2022

Abstract

Abstract PURPOSE: The role of peri-transplant radiation therapy (RT) in young children with primary brain tumors is unclear. We characterized our institutional practice patterns and patient outcomes. MATERIALS AND METHODS: The cohort included all patients treated with high-dose chemotherapy for primary brain tumors at our institution from 2011-2017. Rates of local control (LC), progression-free survival (PFS), overall survival (OS), and radiation-associated injury were assessed. RESULTS: Of 37 eligible patients, 29 (78%) received peri-transplant RT at a median age of 4 years. Patients treated with RT were more likely to have metastatic (p=0.0121) and incompletely resected (p=0.056) disease, and to have high-risk histologies including atypical teratoid rhabdoid tumor, nongerminomatous germ cell tumor, pineoblastoma, primitive neuro-ectodermal tumor, glioneuronal tumor and group 3 medulloblastoma. Of those treated with RT, 13 (45%) received craniospinal irradiation (CSI) and 16 (55%) received focal RT. The median CSI dose was 23.4 Gy (IQR: 18-36; boost median 54 Gy [IQR: 53.7-55.8]) and focal RT dose was 50.4 Gy (IQR: 50.4-54.5). Compared to the focal RT group, patients treated with CSI were older (p=0.0499) and more likely to have metastatic disease (p=0.0004). For the complete cohort, at a median follow-up of 3.8 years, the 2-year rate of LC was 82% (95% CI: 70-96%), PFS was 63% (95% CI: 49-81%), and OS was 65% (95% CI: 51-82%). These rates did not differ significantly between patients treated with and without peri-transplant RT. Two cases of fatal myelopathy were observed after spinal cord doses within the highest tertile (41.4 CGE and 36 Gy); both cases occurred in patients who received RT before high-dose chemotherapy. CONCLUSION: Peri-transplant RT was used for high-risk disease. Oncologic outcomes after RT were encouraging. However, 2 cases of grade 5 myelopathy were observed. If used cautiously, RT may contribute to durable remission in patients at high risk of relapse.