BREAST cancer mortality in women aged 20 to 49 has significantly declined across all racial and molecular subgroups, according to findings presented at the AACR Annual Meeting 2025 in Chicago, Illinois. Despite a steady rise in breast cancer incidence among this age group over the past two decades, new SEER registry data highlight encouraging trends in survival and mortality.
Researchers analyzed 11,661 deaths among women aged 20–49 from 2010 to 2020. Incidence-based mortality decreased from 9.70 per 100,000 in 2010 to 1.47 per 100,000 in 2020. Notably, luminal A breast cancer had the largest mortality drop, particularly in 2017 with a 32.88% annual percent change (APC), while triple-negative breast cancer followed closely with a 32.82% APC drop in 2018.
Despite luminal A’s reputation as the least aggressive subtype, younger women aged 20–39 with luminal A had a lower 10-year relative survival rate (78.3%) than those with luminal B (84.2%), suggesting possible biological heterogeneity in this age bracket.
Striking declines were also seen across racial and ethnic groups. Non-Hispanic Black women had the highest incidence-based mortality in both 2010 and 2020 but also experienced a marked decline beginning in 2016. The steepest APC reductions occurred in non-Hispanic American Indian and Alaska Native women in 2018 (-47.97%) and Hispanic women in 2017 (-30.15%).
Adetunji Toriola, Washington University, emphasized the likely impact of advances in targeted therapy and screening, particularly the uptake of CDK4/6 inhibitors and optimized endocrine treatments introduced post-2015.
The study’s 10-year relative survival analysis also highlighted persistent disparities, with non-Hispanic Black women experiencing the worst survival outcomes, reinforcing the need for equity in care and targeted research.
While the overall decline in mortality represents substantial progress, the study underscores the importance of continued research into tumor biology in younger women and equitable access to high-quality care and early detection strategies.
Reference:
Lyu Y et al. Breast Cancer Mortality in Women Ages 20–49 Significantly Dropped Between 2010 and 2020. 2025. Available at: https://aacr.ent.box.com/s/qim5qkof8og0cepolijpvn2fc6bzpwil. Last accessed: 6 May 2025.
