Why some women with dense breasts may not need supplemental imaging

Imaging providers in the United States are now required by law to notify women about their personal breast density following a mammogram, and that practice has already been in place for years in some states. Many discussions about breast density also include going over the patient’s supplemental imaging options—whether they should consider ultrasound, for instance, or another modality altogether.

According to a new study published in JAMA Internal Medicine, however, providers should consider only discussing supplemental imaging with women with dense breasts if the patients are specifically at a higher risk for breast cancer.

“Studies consistently report that women can experience anxiety or concern in response to breast density notification, and most practitioners are not prepared to counsel women about breast density and are uncertain about offering supplemental imaging,” wrote Karla Kerlikowske, MD, department of medicine at the University of California, San Francisco, and colleagues.

The researchers explored data from more than 630,000 women who underwent more than 1.6 million screening digital mammograms from Jan. 3, 2005, to Dec. 31, 2014. All mammograms were performed at Breast Cancer Surveillance Consortium (BCSC) facilities. Women were only included if they had undergone a prior mammogram, with 30 months being used as a cutoff.

The authors then used that data to compare four different potential strategies for selecting which women should be called in to discuss supplemental imaging: (1) women with an advanced cancer rate of at least 0.61 cases per 1,000 mammograms based on BI-RADS density categories and BCSC five-year risk, (2) women with advanced cancer rates of at least 0.61 cases per 1,000 mammograms based on BI-RADS density categories and the patient’s age, (3) women with advanced cancer rates of at least 0.51 cases per 1,000 mammograms based on BI-RADS density categories and BCSC five-year risk and (4) any women with dense breast tissue.

Overall, women with dense breast tissue made up 47% of the cohort and 60% of the women with advanced cancers. High advanced cancer rates were observed in women with heterogeneously dense breasts and a BCSC five-year risk of 2.5% or higher as well as women with extremely dense breasts and a BCSC five-year risk of 1%.

In addition, the authors noted, women with heterogeneously dense breasts and a five-year risk less than 1.67%—21.7% of the total cohort—had high rates of “false-positive short-interval follow-up recommendation without undergoing supplemental imaging.”

As far as the four potential strategies were concerned, according to the researchers, taking a patient’s risk into account is much more effective than simply looking at their density or age alone.

“Supplemental imaging based on density alone or density plus age was less efficient compared with density-risk strategies,” Kerlikowske et al. wrote. “This finding suggests that breast density notification should be provided but not as a stand-alone risk factor. Breast density notification should incorporate breast cancer risk estimations so women at highest risk of advanced cancer can be appropriately targeted for supplemental imaging and/or considered for primary preventions to reduce risk.”

The team also noted that women at a low risk of advanced cancer should be “reassured that supplemental imaging is not indicated.”