INNV-26. THE CHALLENGE OF TREATING ADULTS WITH MEDULLOBLASTOMA – THE CANON EXPERIENCE

Abstract

Abstract INTRODUCTION Medulloblastoma (MB) is the most common malignant brain tumor in children, but relatively rare in adults. Pediatric treatment paradigms may be applied to young adults despite a paucity of data in this population. Here we aim to describe the characteristics of adults with MB presented at the Canadian Adolescent and Young Adult Neuro-Oncology Network (CANON) multi-disciplinary national rounds along with provider’s current practices in treating these patients. METHODS Cases presented at national rounds between April 2021 – June 2023 including young adults with MB were analyzed to describe patient characteristics and themes of the questions posed. In addition, a survey was sent to all Canadian neuro-oncologists asking about current practice patterns and we describe responses. RESULTS A total of 15 young adults with MB were discussed in this time frame. There were 13 males and 2 females with a median age of 30 years (range 20-61). Subgrouping was available on 12/15, with 7 (46.7%) SHH-activated, 3 (20%) WNT-activated and 3 (20%) Group 4 MB. Ten of the patients presented were new diagnoses with discussion regarding treatment including dose of radiation and chemotherapy protocol. In addition, 4/10 had an incomplete resection and there was discussion regarding a second look surgery. Three patients were presented at time of recurrence, with 2/3 being extra-cranial recurrence. There were a total of 25 responses to the Canadian survey on medulloblastoma, showing variation in practice. Most patients got craniospinal irradiation with 36 Gy. There was wide variation in terms of chemotherapy regimens offered. CONCLUSION There are differences in treatment practices for adults with MB across Canada with many questions regarding what treatment should be offered, specifically related to chemotherapy regimen. This highlights the desperate need to harmonize practice and examine adults as a unique cohort.