Disparities in breast cancer incidence and survival by age, race, and molecular subtype in US women.

Using SEER datasets spanning nearly five decades, we identified a striking longitudinal shift in the breast cancer mortality burden from older to younger women, revealing an evolving risk landscape that warrant challenges to prevailing assumptions about age-related vulnerability. Leveraging contemporary data (2010-2022), we examined how molecular subtype, race, and age intersect jointly to shape survival disparities. As expected, young Black women with triple-negative breast cancer (HR-/HER2-) exhibited significantly elevated hazard ratios, underscoring their urgent need for targeted interventions and prevention strategies. Importantly, we also uncovered disproportionately high mortality risks among Asian women: those under 50 years experienced poorer outcomes for triple-negative breast cancer. These findings suggest that distinct biological, hormonal, and sociodemographic factors may contribute to heterogeneity in cancer progression and survival across populations. In addition, demographic analyses revealed that Asian and Hispanic women have steadily increased in proportional representation, surpassing Black patients recently, underscoring critical population shifts in the breast cancer burden. Together, these results not only broaden current understanding of how age, ancestry, and molecular subtype converge to drive disparities, but also underscore the urgent need to embed these dimensions into personalized prevention, precision diagnostics, and tailored therapeutic strategies to reduce inequities in breast cancer outcomes.