After more than two decades, women between ages 20 and 39 are seeing a slight increase in the rates of breast cancer mortality.
The two decade-plus trend of declining death rates from breast cancer is at an end for women under age 40, prompting experts to call for greater awareness of and more research into the reasons behind this change.
From 1989 to 2017, statistics from the National Center for Health Statistics showed mortality rates from breast cancer among women of all ages declined steeply by 40 percent, largely due to an increase in screening mammography use. But, now, a retrospective analysis, published Feb. 9 in Radiology, shows a slight death-rate increase – 0.5 percent annually – in women ages 20 to 39 between 2010 and 2017.
“It’s clear that mortality rates in women under 40 are no longer decreasing,” said lead study author R. Edward Hendrick, Ph.D., clinical professor of radiology from the University of Colorado School of Medicine. “I estimate that in two-to-three years, the mortality rate will be increasing significantly in these women.”
Among women in each age decade from ages 40 and 79, mortality rates from 2010 to 2017 dropped between 1.2 percent to 2.2 percent. But, the 0.5 percent increase in women between ages 20 and 39 pushed the team to investigate further.
Digging into Surveillance, Epidemiology, and End Results program data, the team that included researchers from Michigan Medicine and Baylor Scott & White Medical Center in Texas, found the metastatic breast cancer incidence rate increase mainly affected white women and that it grew by more than 4 percent annually since 2000 for women in the 20-to-39 age group – a much higher increase than the 1.2 percent rise among women over 40 since 2002. Mortality rates for African American, Asian, Native American, and Hispanic women ages 20 to 39 continued to decline significantly from 1990 to 2017, they said.
*APC: Annual percentage change
Specifically, they added, the metastatic breast cancer rate in women between ages 25 and 39 was 3.84 per 100,000 women in 2015 – a 151-percent increase since 1976 and a 32-percent increase since 2009. These women are more likely to experience aggressive forms of breast cancer, including triple-negative or HER2-positive breast cancer.
Younger women were not the only group to experience an uptick in metastatic breast cancer rates, however. According to their data analysis, the team also identified a 1.85-percent annual rise among women ages 70 to 79 – the steepest increase they saw.
All of these findings shone a light on the importance of screening mammography, they said. For the most part, women under age 40 do not undergo the screening exam. Consequently, their breast cancers are more frequently discovered at a more advanced stage as they are identified via self-examination rather than with imaging.
“The known benefit of screening mammography that has contributed to the mortality decline among women aged at least 40 years is largely absent among women younger than 40 years,” they said.
And, according to a JAMA Internal Medicine study published last year, only 56 percent of women over age 75 still get screened annually – and the more women in that group know about potential over-diagnosis and false positives, the less likely they are to get the scan.
The team said their findings underscore the critical role that mammography plays in driving down the number of breast cancer-related deaths. But, the results also indicate that further research into the slowly increasing mortality rates among younger women is necessary.
“Our hope is that these findings focus more attention and research on breast cancer in younger women and what is behind this rapid increase in late-stage cancers,” Hendrick said.
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