Younger women are outpacing their male peers in cancer incidence, and breast cancer cases are among those on the rise in this demographic. However, a new report shows that a young woman’s likelihood of dying from breast cancer has dropped substantially in recent years.

Research presented late last month at the American Association for Cancer Research (AACR) Annual Meeting analyzed data on breast cancer deaths in women between the ages of 20 and 49 from 2010 to 2020. The team noted that among this group, incidence rates have been going up for about 20 years, so it’s important to understand what that means for mortality and where resources may be needed the most.

The findings showed that, though more young women are getting breast cancer, their death rates have fallen significantly across all cancer subtypes and racial/ethnic groups. Between 2010 and 2020, they fell from 9.70 deaths per 100,000 women to 1.47 per 100,000. The trend was especially noteworthy after 2016.

There were some differences among subtypes, though. Luminal A had the biggest declines, and the more aggressive and difficult to treat triple-negative breast cancer also had a sharp drop. Successful outcomes against luminal A breast cancer varied by age group, though. The 10-year survival rate for luminal A in women aged 20 to 39 was 78.3%, compared to 84.2% for luminal B. For women in their 40s, luminal A survival was better, which researchers say should be the case, as luminal A is supposed to be less aggressive.

Dr. Adetunji Toriola, professor in the Department of Surgery and Division of Public Health Sciences at Washington University School of Medicine, presented the study and says, “This was unexpected as luminal A is generally the least aggressive subtype with the most favorable prognosis. This requires confirmation in other studies but may suggest that luminal A tumors in women ages 20-39 may represent a more biologically heterogeneous and potentially aggressive subgroup.”

In addition to differences related to subtypes, there were differences by racial and ethnic group, as well. Non-Hispanic Black women had the highest mortality rates in 2010 and 2020, at 16.56 and 3.41 per 100,000 women, respectively. In contrast, non-Hispanic white women had the best outcomes in both years, 9.18 deaths per 100,000 in 2010 and 1.16 per 100,000 in 2020.

The 10-year survival rate was also lowest for non-Hispanic Black women, while non-Hispanic white women and Asian/Pacific Islander women had the best rates.

Overall, the researchers say declining mortality can be attributed to treatment advances, more uptake of precision medicine, and expanded access to screening and care for women in their 40s. However, they say there is more work to do.

Dr. Toriola explains, “We must continue to perform impactful research to ensure further reduction in breast cancer mortality, including research into understanding the tumor biology and molecular mechanisms driving carcinogenesis and treatment response in younger women. Additionally, we must encourage and provide access to population-based screening in women ages 40-49 and targeted screening in younger high-risk women, and advocate for access to high-quality treatment and care for all women.”

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