For women aged younger than 40 years, breast cancer mortality rates have stopped declining since 2010, according to a study published online Feb. 9 in Radiology.

R. Edward Hendrick, Ph.D., from the University of Colorado School of Medicine in Aurora, and colleagues analyzed U.S. breast cancer mortality rates by age decade among women aged 20 to 79 years. Female breast cancer mortality rates were analyzed from 1969 to 2017 for all races.

The researchers found that for each age decade from 20 to 79 years, breast cancer mortality rates decreased by 1.5% to 3.4% per year between 1989 and 2010. After 2010, breast cancer mortality rates continued to decline in each age decade from 40 to 79 years by 1.2% to 2.2% per year, but the decline stopped among women aged younger than 40 years. After 2010, for women aged 20 to 29 years and 30 to 39 years, there were nonsignificant increases of 2.8% and 0.3% per year in breast cancer mortality rates, respectively; these increases were mainly attributable to changes in mortality rates in White women. One contributing factor was an increase by more than 4% per year after 2000 in distant-stage breast cancer incidence rates in women aged 20 to 39 years.

"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 in a statement.

Two authors disclosed financial ties to GE Healthcare.