From the Journals

Beyond baseline, DBT no better than mammography for dense breasts


 

FROM THE JAMA OPEN NETWORK

In women with extremely dense breasts, digital breast tomosynthesis (DBT) does not outperform digital mammography (DM) after the baseline exam, according to a review of nearly 1.6 million screenings.

At baseline, DBT improved recall and cancer detection rates for all women. On subsequent exams, differences in screening performance between DBT and DM varied by age and density subgroups. However, there were no significant differences in recall or cancer detection rates among women with extremely dense breasts in any age group.

Kathryn Lowry, MD, of the University of Washington in Seattle, and colleagues reported these findings in JAMA Network Open.

“Our findings suggest that density likely should not be used as a criterion to triage use of DBT for routine screening in settings where DBT is not universally available, as has been reported in physician surveys,” the authors wrote. “The largest absolute improvements of DBT screening were achieved on the baseline screening examination, suggesting that women presenting for their first screening examination are particularly important to prioritize for DBT,” regardless of breast density or age.

Study details

Dr. Lowry and colleagues reviewed 1,584,079 screenings in women aged 40-79 years. The exams were done from January 2010 to April 2018 at Breast Cancer Surveillance Consortium facilities across the United States.

Sixty-five percent of the exams were in White, non-Hispanic women, 25.2% were in women younger than 50 years, and 42.4% were in women with heterogeneously dense or extremely dense breasts. Subjects had no history of breast cancer, mastectomy, or breast augmentation.

The investigators compared the performance of 1,273,492 DMs with 310,587 DBTs across the four Breast Imaging Reporting and Database System density types: almost entirely fatty, scattered fibroglandular density, heterogeneously dense, and extremely dense.

Findings were adjusted for race, family breast cancer history, and other potential confounders.

Recall and cancer detection rates

At baseline, recall and cancer detection rates were better with DBT than with DM, regardless of breast density subtype or patient age.

For instance, in women aged 50-59 years, screening recalls per 1,000 exams dropped from 241 with DM to 204 with DBT (relative risk, 0.84; 95% confidence interval, 0.73-0.98). Cancer detection rates per 1,000 exams in this age group increased from 5.9 with DM to 8.8 with DBT (RR, 1.50; 95% CI, 1.10-2.08).

On follow-up exams, recall rates were lower with DBT for women with scattered fibroglandular density and heterogeneously dense breasts in all age groups, as well as in women with almost entirely fatty breasts aged 50-79 years.

“By contrast, there were no significant differences in recall rates in women with extremely dense breasts in any age group,” the authors wrote.

Cancer detection rates on follow-up exams varied by age and breast density.

Cancer detection rates were higher with DBT than with DM in women with heterogeneously dense breasts in all age groups and in women with scattered fibroglandular density at 50-59 years of age and 60-79 years of age. However, cancer detection rates were not significantly different with DBT or DM for women with almost entirely fatty breasts or extremely dense breasts of any age.

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