Mammographic sensitivity for detecting breast cancer was only 71 percent for women with dense breasts, compared to 82 percent for women with non-dense breasts. Cancers detected at screening were more advanced among women in the dense breast tissue group. Average tumor diameter for screen-detected cancers was 16.6 millimeters (mm) in the dense breasts group, compared to 15.1 mm for the non-dense group. Lymph-node-positive disease was found in 24 percent of women with dense breasts, compared with 18 percent for women with non-dense breasts.

The results add another piece to the puzzle of screening protocols for women with dense breasts. Dr. Hofvind noted that more than half of states in the U.S. have enacted breast density legislation, with some states requiring that women be informed about their breast density or that additional imaging could be beneficial. However, supplemental screening for women with dense breasts currently is not recommended by any of the major health care societies or organizations, and more research is needed before widespread changes are made.


"We need well-planned and high-quality studies that can give evidence about the cost-effectiveness of more frequent screening, other screening tools such as tomosynthesis and/or the use of additional screening tools like MRI and ultrasound for women with dense breasts," she said. "Further, we need studies on automated measurement tools for mammographic density to ensure their validity."

In the meantime, Dr. Hofvind said, the findings will help inform how automated volumetric density categorization will change population-based screening performance and outcomes through a more objective breast density measurement method.

In an accompanying editorial, "Machine Detection of High Breast Density: Worse Outcomes for Our Patients," Liane E. Philpotts, M.D., FACR, from Yale School of Medicine writes, "This study is important for two main reasons: (1) the validation that automated means of density classification can correctly identify a percentage of women with dense tissue, and (2) women with dense tissue have poorer performance of screening mammography. It lends support to the density notification movement along with redoubling efforts towards optimizing supplemental screening methods."

She added that automated volumetric determination could better standardize density measurements and provide greater confidence that women with dense breast tissue could consistently be identified.

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