MDB-18. MOLECULARLY-DEFINED MEDULLOBLASTOMA: POPULATION-LEVEL PATTERNS IN THE UNITED STATES, 2018-2019

Abstract Medulloblastoma is one of the most common types brain and other CNS tumors among pediatric population in US. Molecularly-defined tumor histopathologies—including medulloblastoma subtypes—were incorporated into US cancer registry reporting for individuals with beginning 2018. We assessed epidemiology overall survival (OS) patterns children adolescents, highlighting molecularly-defined subtypes. Children adolescents (0-19 years) that were histopathologically diagnosed from 2018-2019 had molecular marker data identified within Commission on Cancer’s National Cancer Database (NCDB) Central Brain Tumor Registry United States databases, which combines CDC’s Program Registries (NPCR) NCI’s Surveillance, Epidemiology, End Results (SEER) Programs. Incidence rates per 100,000 95% confidence intervals (95CI) estimated histopathologies ≥16 cases. One-year OS was using NCDB ≥50 cases follow-up through 2020 Kaplan-Meier methods. There 601 histopathologically-confirmed 2018-2019, 39.6% available subtype information. Overall incidence 0.37 (95CI=0.34-0.40). subtypes 0.05 (95CI=0.04-0.06) SHH-activated & TP53wt, 0.02 (95CI=0.01-0.02) WNT-activated, 0.08 (95CI=0.06-0.09) nonWNT/nonSHH, while TP53mut too rare to calculate incidence. all 96.6% (95CI=92.1%-100.0%). nonWNT/nonSHH (95CI=92.8%-100.0%), TP53wt 93.7% (95CI=87.1%-100.0%). Other occurred rarely survival. Our findings provide initial epidemiological estimates adolescents. As improvements collection completeness lead increased availability, robustness these will increase. Collection are essential understanding this important childhood adolescent tumor.