An ahead-of-print article in the December issue of the American Journal of Roentgenology comparing dense breast ultrasound (US) screening after digital mammography (DM) versus after digital breast tomosynthesis (DBT) yielded “no significant difference” in additional cancer detection rate.

Lead investigator Elizabeth H. Dibble, MD, of Brown University in Providence, R.I., and colleagues retrospectively searched databases at two tertiary breast imaging centers and an office practice, focusing on 3,183 screening breast ultrasound examinations performed from October 2014 to September 2016—1,434 (45.1%) after DM and 1,668 (52.4%) after DBT.

Of these 3,183 examinations, 81 (2.5%) had no prior mammogram available. Of the 122 DM and DBT patients for whom biopsy or cyst aspiration was recommended—all BI-RADS assessment category 4 or 5 studies—118 (96.7%) had biopsy or cyst aspiration results available. Moreover, of the 36 biopsies or aspirations after DM, six (16.7%) were malignan, and 30 (83.3%) were benign. And of the 82 biopsies or aspirations after DBT, 11 (13.4%) were malignant, and 71 (86.6%) were benign (p = 0.8583).

Overall, the additional cancer detection rate by ultrasound after DM was 5/1,434, or 3.5 per 1,000 women screened; after DBT, the detection rate was 5/1668, or three per 1,000 women screened (p = 0.9999).

To Dibble, these numbers are telling. “DBT does not obviate additional US screening in women with dense breast tissue. No evidence was found of a difference in additional cancer detection rate with screening US after DM versus after DBT,” she says.

Dibble adds: “Knowing that the cancer yield of screening US is similar after DBT versus DM may help inform clinical practice because questions abound about whether DBT is sufficient screening for women with dense breast tissue.”