Breast Density Doesn’t Increase Risk of Dying from Cancer

Women with dense breasts have an increased risk of developing breast cancer, but that doesn’t raise their risk of dying from breast cancer, according to a study in the Journal of the National Cancer Institute. This finding reinforces the need for women to undergo regular mammograms, industry groups said in response.

Researchers from the National Cancer Institute in Maryland evaluated the relationships between mammography density and risk of death from breast cancer among 9,232 women who were diagnosed with primary invasive breast cancer from 1996 to 2005. The group of women with dense breast tissue, as determined by the Breast Imaging Reporting and Data System (BI-RADS) density classification, were compared with women with scattered fibroglandular densities.

Of 1,795 women who died, 889 died of breast cancer, but there was no connection found between breast density and death.

“It was reassuring that elevated breast density, a prevalent and strong breast cancer risk factor, was not associated with risk of breast cancer death or from any cause in this large prospective study,” wrote the authors.

The American College of Radiology (ACR) and the Society of Breast Imaging (SBI) called the study “reassuring for women with dense breast tissue.” The groups pointed out that although some cancers may be missed by mammograms in women with dense breasts, screening with ultrasound or MRI may provide many more false alarms with this type of screening compared with mammography.

“It is important to remember that mammography is the only test that has been shown in randomized, controlled trials (the most rigorous scientific studies) to actually save lives,” according to a statement from the groups.

The groups encouraged support for more studies with ultrasounds and MRI, in addition to mammography, to further reduce the death rate.