Breast cancer mortality rates have stopped declining for women over 74 and under 40, largely due to rising diagnoses of advanced-stage cancer.
A new study published in the Journal of Breast Imaging by Oxford University Press reveals that the decline in breast cancer mortality rates has stalled in women over 74. It also confirms that mortality rates in women under 40 have remained unchanged, reaffirming previous findings. The stagnation in mortality decline among older women is a newly observed trend.
Breast cancer is the second leading cause of cancer-related deaths among American women, with over 42,000 deaths expected in 2024. Before 1990, breast cancer incidence was rising, and mortality rates were either stable or increasing. However, since 1990, breast cancer deaths have steadily declined, largely due to widespread mammography screening and advancements in treatment.
The researchers, Debra Monticciolo and R. Edward Hendrick, assessed cancer mortality rates collected and maintained by the National Center for Health Statistics since 1990. For U.S. women overall breast cancer mortality rates have decreased steadily from 1990 to 2022, falling by 43.5% over that period. The most recent trend has been a decrease of 1.23% per year from 2010 to 2022, the lowest rate of decrease recorded since 1990.
Age and Racial Disparities in Mortality Trends
For U.S. women ages 20 to 39 (combining all races/ethnicities), breast cancer mortality rates decreased by 2.79% per year from 1990 until 2010, but have remained flat since 2010.
The investigation found that for women 75 years and older, the breast cancer mortality rate decreased by 1.26% per year from 1993 to 2013, when the rate stopped declining. For Asian, Hispanic, and Native American women (of all ages), breast cancer mortality rates have stopped declining over the most recent period: since 2009 for Asian women, since 2008 for Hispanic women, and since 2005 for Native American women.
Previous research indicated that breast cancer mortality rates stopped declining for women under 40 in 2010. The researchers here found that in both younger and older groups, the end of mortality rate decline was primarily due to mortality rates no longer declining for White women under 40 and over 74, as well as unfavorable trends for Hispanic women ages 20-39 years and for Asian, Hispanic, and Native American women 75 and older. Breast cancer mortality rates in Black women continued to decline in all age groups.
Potential Causes of Stagnation in Mortality Rate Decline
The investigators conducting this study contend that mortality rates have stopped declining for women under 40 and over 74 due to significant increases in stage IV breast cancers at diagnosis in these two age groups. Stage IV (metastatic) breast cancer at diagnosis has an extremely poor prognosis: a 31% 5-year survival rate.
This study indicates that increasing rates of advanced-stage breast cancer at diagnosis is an important reason breast cancer mortality rates are no longer declining at the rate they once did. The researchers believe that this may be due to healthcare protocols. While the medical community currently recommends a breast cancer assessment for all women by age 25, breast cancer screening is only recommended for women under age 40 who are at higher-than-average risk. Some guidelines discourage women over 74 from screening.
Breast cancer mortality rate ratios for Black vs White women show the widest gap for women under age 40 years, suggesting that younger Black women are especially in need of alternatives to our current breast cancer risk assessment, screening, and treatment strategies, according to the authors.
“The fact that breast cancer mortality rates have stopped declining for women over age 74 is an alarming new trend,” said Monticciolo. “This is in addition to women under age 40 no longer seeing mortality rates decline from breast cancer. These groups are exactly those discouraged from breast cancer screening by some U.S. guidelines.”
Reference: “Recent Trends in Breast Cancer Mortality Rates for U.S. Women by Age and Race/Ethnicity” by Debra L Monticciolo and R Edward Hendrick, 6 March 2025, Journal of Breast Imaging.
DOI: 10.1093/jbi/wbaf007
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