Racial/ethnic and sex differences in young adult malignant brain tumor incidence by histologic type.

Background: Brain tumors are among the top four cancers in young adults. We assessed important windows of tumor development and examined the interplay of race/ethnicity, age, and sex in young adult brain tumor incidence.

Methods: Using SEER 18 data (2000-2017), incidence rates were estimated by Poisson regression in individuals aged 20-39 years at diagnosis. Incidence rate ratios (IRR) and 95% confidence intervals (95% CI) were estimated by race/ethnicity, sex and age for 12 malignant histologies.

Results: White incidence for all histologies was higher (White vs. Black IRR: 2.09, 95% CI: 1.94, 2.24; White vs Asian Pacific Islander IRR: 1.88, 95% CI: 1.75, 2.03; White vs Hispanic IRR: 1.70, 95% CI: 1.62, 1.78; White vs American Indian IRR: 1.40, 95% CI: 1.14, 1.73). Minority groups had higher lymphoma incidence (White vs Black IRR: 0.32, 95% CI: 0.25, 0.40, White vs Hispanic HR: 0.55, 95% CI: 0.44, 0.68). Males had higher incidence than females for all histologies (IRR: 1.36, 95% CI: 1.31, 1.41). Male rates were highest for lymphoma (male-to-female [MF] IRR: 2.00, 95% CI: 1.65, 2.42) and glioblastoma (MF IRR: 1.61, 95% CI: 1.48, 1.75). The male excess in incidence was similar by race/ethnicity and increased with age (20-24-year-old IRR: 1.18, 95% CI: 1.07, 1.29; 35-39-year-old IRR: 1.44, 95% CI: 1.35, 1.54).

Conclusions: A White race and male incidence excess was observed among brain tumors.

Impact: The male excess was similar by race/ethnicity and increased with age suggesting male sex may be an intrinsic risk factor for brain tumor development.