Breast cancer death rates have stopped declining for women in the United States younger than age 40, ending a trend that existed from 1987 to 2010, according to a report published by Hendrick et al in Radiology.
Breast cancer is the most common nonskin cancer and the second most common cause of cancer deaths in women in the United States, accounting for 30% of all cancers in women. Although most invasive breast cancers occur in women aged 40 and older, 4% to 5% of cases happen in women younger than 40.
Statistics have shown steady decline in overall breast cancer mortality rates for American women since 1989. From 1989 to 2017, breast cancer mortality rates for all women in the U.S. decreased by 40%, a decrease attributed to improved treatment and increased rates of screening mammography use starting in the early to mid-1980s.
Recent Trends in Mortality Rates
In the new study, researchers determined U.S. trends in female breast cancer mortality rates by 10-year age subgroups based on recent data from the National Center for Health Statistics. Analysis showed that from 2010 to 2017, mortality rates decreased between 1.2% and 2.2% per year for women in each age decade from 40 to 79 years, but increased by a nonsignificant 0.5% per year for women aged 20 to 39.
“It's clear that mortality rates in women under 40 are no longer decreasing,” said lead study author R. Edward Hendrick, PhD, Clinical Professor in the Department of Radiology at the University of Colorado School of Medicine. “I estimate that in 2 to 3 years, the mortality rate will be increasing significantly in these women.”
The changing mortality rate in younger women is likely related to an increase in distant-stage, or metastatic, breast cancers. The authors’ analysis of invasive breast cancer incidence rates from the Surveillance, Epidemiology, and End Results program found that distant-stage breast cancer incidence rates have increased by over 4% per year since the year 2000 in women aged 20 to 39—a much higher rate of increase than in women aged 40 and over.
Unlike breast cancer treatments, imaging recommendations for early detection vary by age. Women 40 and older are offered screening mammography for early breast cancer detection, and over half of these women report being screened regularly. Screening is not done for women younger than 40 unless they are known to be at high risk for breast cancer.
According to the researchers, the continued decline in death rates in women over age 40 may reflect the benefit of regular screening for women in this age group. The difference in mortality trends for women younger than 40 and older than 40 provides further evidence for the essential role mammography screening plays in decreasing breast cancer deaths, they said.
The researchers plan to continue studying these trends to learn more about why mortality rates have stopped declining in younger women.
“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,” concluded Dr. Hendrick.
Disclosure: For full disclosures of the study authors, visit pubs.rsna.org.The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.