Since 1989, between 384,000 and 615,000 women’s lives have been spared thanks to significant advancements in breast cancer screening methods and treatment, a study reports.

The findings of the study, “Breast cancer deaths averted over 3 decades,” were published in Cancer.

Statistics from the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) program indicate that between 1975 and 1990, breast cancer mortality rates increased by 0.4% every year in the U.S.

Since 1990, however, mortality rates dropped by 1.8% each year until 1998, and then even further, by 3.4% per year until 2015.

“This decrease has been attributed to the increased use of screening mammography combined with improved breast cancer treatment,” the researchers said.

Screening mammography became a popular and widely available method for breast cancer detection since the mid-1980s, and its use rose into the early 2000s. According to mathematical models developed by the Cancer Intervention and Surveillance Modeling Network (CISNET), screening mammography was responsible for a reduction of 28-65% in breast cancer deaths in the year 2000, and the remaining decrease was linked to progress in breast cancer therapies.

In this study, three scientists — R. Edward Hendrick, PhD, of the University of Colorado School of Medicine, Jay Baker, MD, of Duke University Medical Center, and Mark Helvie, MD, of the University of Michigan Health System — came together to estimate how many deaths have been averted in total over the last 30 years due to the combination of improved screening and treatment methods.

The study was based on population data from the SEER program on breast cancer mortality rates among women ages 40–84 living in the U.S. The data was used to estimate the number of averted deaths in 2012 and 2015, as well as to extrapolate the number of averted deaths in 2018.

Results showed reductions in breast cancer mortality rates ranged from 38.6–50.5% in 2012, from 41.5–54.2% in 2015, and from 45.3–58.3% in 2018. From 1989 to 2018, between 384,046 and 614,484 breast cancer deaths were avoided thanks to a combination of better screening methods and treatment options.

“Recent reviews of mammography screening have focused media attention on some of the risks of mammography screening, such as call-backs for additional imaging and breast biopsies, downplaying the most important aspect of screening — that finding and treating breast cancer early saves women’s lives. Our study provides evidence of just how effective the combination of early detection and modern breast cancer treatment have been in averting breast cancer deaths,” R. Edward Hendrick, PhD, the study’s corresponding author, said in a news release.

However, Hendrick said that currently only about half of U.S. women over 40 follow the recommendations and have a yearly mammogram.

“The best possible long-term effect of our findings would be to help women recognize that early detection and modern, personalized breast cancer treatment saves lives and to encourage more women to get screened annually starting at age 40,” he said.

“While we anticipate new scientific advances that will further reduce breast cancer deaths and morbidity, it is important that women continue to comply with existing screening and treatment recommendations,” Helvie said.