US yields similar cancer detection rates after digital mammography, DBT

Screening ultrasound (US) examinations after digital breast tomosynthesis (DBT) and after digital mammography (DM) result in comparable cancer detection rates, according to a new study published in the American Journal of Roentgenology.

DBT continues to gain popularity throughout the United States, but researchers are still learning more about its impact on patient care.

“Compared with DM, DBT improves detection of breast cancer in women with dense breasts,” wrote Elizabeth H. Dibble, MD, Rhode Island Hospital in Providence, and colleagues. “The value US screening adds in patients who have already undergone mammographic screening with DBT remains unclear.”

Dibble et al. explored data from two breast imaging centers and an office-based practice, focusing on more than 3,000 screening breast US examinations performed from October 2014 to September 2016. While 45.1% occurred following DM, 52.4% occurred after DBT. Overall, the additional cancer detection rate for US after DM was 3.5 per 1,000 women. For US after DBT, that number was 3.0 per 1,000 women. While 13.4% of the biopsies or aspirations after US and DBT were malignant, 16.7% of biopsies or aspirations after US and DBT were malignant.

“Our study found no evidence to suggest a difference in additional cancer detection rate with screening US after DM versus after DBT,” the authors wrote. “These findings suggest that patients who have undergone screening mammography with DBT maintain a similar benefit of detecting mammographically occult cancers on screening US compared with patients who have undergone screening mammography with DM.”

In addition, the team added, “no evidence” was found that there was a difference in the time to cancer detection between the two modalities. This means there is no specific timing for screening US after DM or DBT.

“Some patients undergo screening mammography and screening US on the same day, likely for convenience; others may present shortly after screening mammography in response to their breast density notification letter; still others may present at six months or even greater than six months after screening mammography to optimize the chance of identifying an interval cancer,” the authors wrote.