Differences in Primary Molecular Subtype Distribution Contribute to Racial and Ethnic Disparities in Adult-Type Diffuse Gliomas

BACKGROUND: Molecular profiling has become an integral part of glioma classification. The extent to which incidence of molecularly-defined adult-type gliomas vary by demographics is unknown. We describe national-level incidence and overall survival patterns of selected glioma subtypes by race/ethnicity. METHODS: We generated standardized average annual age-adjusted incidence rates of molecularly-defined glioma subtypes by race/ethnicity from the Central Brain Tumor Registry of the United States (CBTRUS) using newly-diagnosed cases from January 1, 2018 to December 31, 2022. Survival data from the National Cancer Database (NCDB) were used from newly-diagnosed cases from January 1, 2018 to December 31, 2021 (with follow up through December 31, 2022) to evaluate four-year overall survival, median survival, and multivariable Cox Proportional hazards ratios. RESULTS: CBTRUS identified 68,172 glioma cases, IDH-wildtype glioblastoma was most common (n = 51,548). Non-Hispanic White individuals had significantly higher incidence of all gliomas compared to other groups (p > 0.001). Non-Hispanic Black individuals had the lowest incidence for IDH-mutant astrocytoma and oligodendroglioma, and shared lowest incidence of IDH-mutant glioblastoma and IDH-wildtype astrocytoma with non-Hispanic other individuals, who had the lowest incidence of IDH-wildtype glioblastoma (p < 0.001). The odds of having an IDH-wildtype (versus IDH-mutant) astrocytoma or glioblastoma were significantly lower for males, those of older age, and non-Hispanic Black individuals (p < 0.001). Non-Hispanic other individuals also had increased adjusted overall survival for most glioma subtypes compared to other racial/ethnic groups (p < 0.001). Four-year overall survival was lowest in all racial/ethnic groups for IDH-wildtype glioblastoma (p < 0.001). CONCLUSIONS: Our findings reveal significant disparities in incidence and survival by race/ethnicity with notable variations present based on glioma biomarkers.