Young Women's Breast Cancer Deaths Plummet Over Decade

Medscape

08-05-2025

Despite the rising incidence rates of breast cancer among younger women, advances in treatment and detection appear to reduce breast cancer mortality in this population.
New research highlights a substantial improvement in survival outcomes across all molecular subtypes and racial groups, suggesting that precision medicine approaches are having meaningful impacts, even as the disease becomes more common in women younger than 50 years. The results of a study presented at the American Association for Cancer Research (AACR) Annual Meeting 2025, which analyzed trends across molecular subtypes and racial groups, adds granularity to the recent Annual Report to the Nation on the Status of Cancer and the Breast Cancer Statistics 2024 report.
The research presented at the meeting focuses specifically on younger women aged 20-49 years, a group often underrepresented in cancer mortality analyses. Its findings, which are currently under peer review for publication, suggest that advances in breast cancer management are making significant impacts on survival outcomes for younger women, according to Adetunji Toriola, MD, PhD, MPH, who presented the findings at a press conference, at AACR.
Study Rationale and Methodology
The research was motivated by the team's earlier findings showing increases in breast cancer incidence among younger women in the United States; increases in breast cancer incidence were observed across all ethnic and racial groups.
'One of the most fascinating findings in this study was that the incidence of breast cancer among women of the more recent birth cohort, particularly in the 1980 birth cohort, was 25% higher than women of previous birth cohorts,' said Toriola, professor of surgery and co-lead of the Cancer Prevention Program at Siteman Cancer Center, Washington University School of Medicine, St. Louis, during the press conference.
This rising incidence prompted the researchers to investigate whether mortality patterns followed similar trends. Using SEER-17 registry data, they analyzed 112,826 breast cancer cases and 11,661 breast cancer–specific deaths among women aged 20-49 years diagnosed with primary invasive breast cancer between 2010 and 2020.
The team used incidence-based mortality methodology, which 'allows for more precise attribution of deaths to the specific cancer diagnosis compared to mortality estimates from death certificates,' Toriola said. Joinpoint regression models were used to identify significant changes in mortality trends over time.
Marked Declines Across Subtypes and Racial Groups
The analysis revealed substantial drops in mortality across all molecular subtypes, with particularly sharp declines beginning around 2016. Overall, incidence-based mortality declined from 9.70 per 100,000 in 2010 to 1.47 per 100,000 in 2020. This decline was consistent across molecular subtypes, including luminal A, luminal B, human epidermal growth factor receptor 2 (HER2)–enriched, and triple-negative breast cancer (TNBC).
For luminal A breast cancer, mortality decreased consistently from 2010, with a more pronounced decline after 2017 (annual percent change [APC], −32.88; 95% CI, −55.17 to −21.30). TNBC showed a similar pattern, with a marked decline beginning in 2018 (APC, −32.82; 95% CI, −41.47 to −17.79).
When examined by race and ethnicity, the data showed substantial improvements across all groups, though racial disparities persist. Non–Hispanic Black women had higher incidence-based mortality in both 2010 (16.56 per 100,000) and 2020 (3.41 per 100,000) than non–Hispanic White women (9.18 per 100,000 in 2010 and 1.16 per 100,000 in 2020).
'In other races, we had a cluster of about between 7 and 10 per 100,000 women for incident-based mortality in 2010, which reduced to between 1 and 2 per 100,000 in 2020,' Toriola noted during the press conference.
Importantly, the data indicated more pronounced mortality reductions beginning around 2016-2017 in many subgroups. For non-Hispanic American Indian and Alaska Native women, there was an almost 50% reduction in incidence-based mortality from 2018 onward. Toriola attributed these accelerated improvements to the introduction of novel targeted therapies during this period.
Age- and Subtype-related Survival Differences
The study highlighted marked long-term survival differences between age subgroups. Women aged 20-39 years had an 86.6% 5-year relative survival compared with 92% for women aged 40-49 years, while 10-year survival rates were 78.5% and 87.6%, respectively. According to Toriola, this finding highlights the need for targeted screening in high-risk populations younger than 40 years.
Younger women 20-39 years old with luminal A breast cancer showed worse survival outcomes than those with luminal B cancer after the 5-year mark. Toriola described this finding as unexpected, as luminal A breast cancer is typically considered to have the most favorable prognosis.
'We noticed that at the start of follow-up, the survival rates for women with luminal A and luminal B were identical, but this graph started separating as early as year 1,' explained Toriola. 'By year 5, the 5-year relative survival for women with luminal B was better than for women with luminal A, which is not what we would expect.'
When asked about this finding, Ann Partridge, MD, MPH, of Dana-Farber Cancer Institute, Boston, who was not involved in the study, said that, although unexpected, this phenomenon has been observed previously.
'This is consistent with what we see clinically and have seen in prior studies,' Partridge stated in an interview. She referenced previous research documenting this pattern in younger women with breast cancer.
Persistent Racial Disparities in Survival
Although overall mortality decreased, survival analyses revealed that non–Hispanic Black women continue to have the worst survival outcomes. At the 10-year follow-up, all racial groups except non–Hispanic Black women had relative survival rates above 80%. For non–Hispanic Black women, the 10-year relative survival rate was 75.5%.
When asked about factors contributing to persistent racial disparities, Partridge emphasized: 'I think much of the story here is access to care and treatment, and adherence to therapy. I am not sure of any clear biological or treatment response issues that have been validated definitively in this setting.'
Although the higher overall mortality among Black women with breast cancer aligns with the Annual Report to the Nation on the Status of Cancer and the Breast Cancer Statistics 2024 report, the research presented at the AACR went one step further to analyze racial disparities in long-term survival by tumor subtype specifically in younger women. The lowest long-term mortality across subtypes and races was observed for non–Hispanic Black women with TNBC (10-year survival: 67.1%), followed by Hispanic women with TNBC (10-year survival: 70.8%) and non–Hispanic Black women with ERBB2-enriched breast cancer (10-year survival: 74.1%).
Therapeutic Advances Driving Improved Outcomes
Toriola suggested that the dramatic mortality reductions, particularly after 2016, likely reflect significant advances in breast cancer management, particularly novel targeted therapies.
When asked about therapeutic advances that have likely contributed to improved outcomes in younger patients with breast cancer, Partridge said: 'For young-onset patients, the majority of whom have ER+ disease, the increasing role of ovarian function suppression and addition of aromatase inhibitors and associated risk reduction in early stage disease likely is having a big effect.'
Partridge added that young women are also more likely to have TNBC or HER2+ disease, two of the more aggressive subtypes that now have new therapies, including immunotherapy and anti-HER2 therapy, respectively. 'Their increasing use and associated survival advantages are also improving young-onset disease outcomes,' she said.
When questioned about the relative contribution of screening vs treatment advances, Toriola noted, 'Both have contributed significantly to reductions in mortality.' Indeed, a 2024 study estimating the number of breast cancer deaths averted from prevention, screening, and treatment efforts between 1975-2020 showed that treatment advances contributed to about 75% of the deaths averted, and mammography screening contributed to the remaining 25% of the deaths averted.
Clinical Implications
Considering the lower 10-year survival among women aged 20-39 years than women aged 40-49 years, Toriola suggested that targeted screening in high-risk populations aged 40 years or younger may be needed.
Although Partridge does not believe that the results presented at the conference should immediately alter current screening recommendations by the United States Preventive Services Task Force, which recommends biennial mammography starting at the age of 40 years, she noted that younger women who are at risk might benefit from earlier screening. 'We need to develop better tools for screening and better tools and communications to identify young people at high risk who warrant earlier screening,' she said in the interview.
For clinicians treating younger patients with breast can, Partridge emphasized the importance of personalized approaches: 'Carefully and tailored treatment is needed, targeting the tumor in consideration of the host, including issues unique to or accentuated by young age onset, such as fertility and genetics.'
Toriola concluded his presentation by outlining future research directions: 'We need to continue impactful research to ensure that there is a continued reduction in mortality and that we understand the biologic mechanisms driving incidence and response to treatment.'
Toriola and Partridge had no financial relationships to disclose.