PATH-45. OUTCOMES OF AN IRRADIATION SPARING APPROACH IN MEDULLOBLASTOMA BY SUBGROUP IN YOUNG CHILDREN: AN INSTITUTIONAL REVIEW

Abstract

Abstract OBJECTIVE To describe disease outcomes including overall survival and relapse patterns by subgroup in young pediatric patients treated for medulloblastoma with an irradiation-sparing approach. METHODS Retrospective analysis of clinical outcomes including treatment, relapse and salvage therapy and late effects in children treated for medulloblastoma with a radiation-sparing approach at British Columbia Children’s Hospital (BCCH) between 2000 and 2020. RESULTS There were 30 patients (median age 2.8 years, 60% male) treated for medulloblastoma with a radiation-sparing approach at BCCH. Subgroups included Sonic Hedgehog (SHH, (n=14), Group 3 (n=7), Group 4 (n=6) and indeterminate status (n=3). Three and 5-year event-free survival (EFS) and overall survival (OS) were 49.0% (30.2 and 65.4%) and 42.0% (24.2-58.9%) and 62.5% (42.4 and 77.2%) and 66.0% (95% CI 46.0-80.1%) and 62.5% (95% CI 42.5 and 77.2%) respectively, with a median follow up of 9.5 years. Relapse occurred in 12/25 patients following a complete response, of whom six (Group 4: n=4, Group 3: n=1, unknown: n=1) were successfully salvaged with craniospinal axis (CSA) RT and remain alive at a median follow up of seven years. Disease/treatment-related morbidity included endocrinopathies (n=8), hearing loss n=16), and neurocognitive abnormalities (n=9). CONCLUSIONS This radiation sparing treatment approach for young patients with medulloblastoma resulted in a durable cure in most patients with SHH subgroup medulloblastoma. In those patients with Group 3 and 4 medulloblastoma, relapse rates were high; however, most Group 4 patients were salvaged with RT.