Ethnic Disparities in Incidence and Prognosis of Molecularly Defined Adult-Type Diffuse Glioma

Racial and ethnic disparities in the incidence and prognosis of adult-type diffuse glioma (ADG) are well-documented, but previous research was limited by outdated histologic classifications and the aggregation of heterogeneous Asian populations. This study aimed to re-evaluate these disparities using contemporary molecular classifications and granular ethnic data, with a focus on  isocitrate dehydrogenase (IDH) wild-type glioblastoma.

This was a population-based cohort study using data from the US SEER program. The study included patients with molecularly defined ADG per the 2021 WHO CNS Classification. Age-adjusted incidence rates were calculated, and overall survival (OS) was analyzed using the Kaplan-Meier method, multivariable Cox regression, propensity score matching, and multiple imputation. The Asian/Pacific Islander (API) group was disaggregated into specific ethnicities for survival analysis.

Non-Hispanic White (NHW) patients had the highest incidence of ADG and all molecular subtypes. In patients with IDH wild-type glioblastoma, analysis showed that Hispanic (hazard ratio [HR], 0.88 [95% CI, 0.80 to 0.96]), Non-Hispanic Black (HR, 0.80 [95% CI, 0.71 to 0.91]), and API (HR, 0.77 [95% CI, 0.67 to 0.88]) patients had significantly better OS than NHW patients. Disaggregation of the Asian category revealed that this advantage was driven almost exclusively by patients of Chinese ethnicity, who demonstrated a profound survival benefit (HR, 0.58 [95% CI, 0.43 to 0.77]; P < .001). This finding was robust across multiple sensitivity analyses. No significant prognostic differences were found for IDH-mutant gliomas.

In the molecular era, NHW individuals have the highest incidence of ADG. However, patients of Chinese-and more broadly East Asian-ethnicity with IDH wild-type glioblastoma exhibit a pronounced and robust survival advantage. This highlights the critical need to consider ancestral diversity in future glioma research to uncover biological mechanisms and improve patient outcomes.