DBT doesn’t benefit subset of women facing higher breast cancer risk, poorest mammography outcomes

For most women, digital breast tomosynthesis is better than digital mammography at detecting cancer and reducing recall visits. New research, however, has pinpointed a subset of women who don’t experience these typical benefits.

The investigation, published Tuesday in JAMA Network Open, included more than 1.5 million breast exams. And while women with dense breasts largely saw a boost in cancer detection with DBT, also known as 3D mammography, a small percentage of higher-risk patients did not.

“DBT is improving screening outcomes for the vast majority of women getting screening mammography,” Kathryn Lowry, MD, assistant professor of radiology at the University of Washington School of Medicine in Seattle, said in a statement. “Unfortunately, it does not seem to benefit the 10% of women who have extremely dense breasts and who already experience the poorest of mammography outcomes today.”

DBT was first approved by the Food and Drug Administration in 2011, and several studies have shown its superiority for detecting cancer, reducing ambiguous findings, and accurately measuring tumor size compared to traditional breast screening approaches. Such gains have been praised as benefiting all women.

Many of these prior studies have not compared subgroups of women, according to Lowry. So, the researchers set out to do just that, analyzing 1.3 million digital mammo exams and more than 310,000 DBT scans. They keyed in on cancers detected, patient recalls by age group, breast densities and baseline versus subsequent exams.

For women ages 40-79 undergoing their first screening exam, DBT led to greater improvements in reducing recall and improving cancer detection. Most also experienced these positives in their follow-up exams. For individuals with “extremely dense” breasts, meanwhile, DBT didn’t make much of a difference compared to digital mammography.

Importantly, Lowry did note that patients with dense breasts saw the largest gains in detection when undergoing DBT. Nearly half of all women fall into this category, with fewer (10%) considered to have “extremely dense” breasts.

“Our findings can help providers and patients better decide how to make decisions about screening mammography,” Lowry noted. “If a provider only has access to one or two DBT machines, it will help them determine which patients should get priority with those. If a patient has to pay more out of pocket or drive several hours to reach a provider who offers DBT, this can help them know whether they’re likely to experience benefit,” she added.