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Ultrasound yields similar cancer detection rates after digital mammography or after tomosynthesis

The Flow Chart of the study carried out by (Dibble EH et al. Dense Breast Ultrasound Screening After Digital Mammography Versus After Digital Breast Tomosynthesis. AJR Am J Roentgenol. 2019 Sep 25: 1-6. doi: 10.2214/AJR.18.20748

US = ultrasound, DM = digital mammography, DBT = digital breast tomosynthesis. Credit American Journal of Roentgenology (AJR)

Dense breast ultrasound screening after digital mammography –  versus after digital breast tomosynthesis – yielded ‘no significant difference’ in additional cancer detection rate

The majority of data available on screening breast ultrasound are from patients screened after digital mammography (DM), and not after digital breast tomosynthesis (DBT). Compared to DM, DBT improves detection of breast cancer in women with dense breasts. The value that US screening adds in patients who have already undergone mammographic screening with DBT remains unclear.

Given the enhanced cancer detection with DBT, a group of researchers from Brown University  hypothesized that fewer cancers would be identified by US after DBT compared to after DM. They carried out a study to compare the yield of dense breast US screening after DM versus after DBT by comparing additional cancers or other findings requiring biopsy in patients with dense breasts who undergo US screening after DM or DBT (Dibble EH et al. Dense Breast Ultrasound Screening After Digital Mammography Versus After Digital Breast Tomosynthesis. AJR Am J Roentgenol. 2019 Sep 25: 1-6. doi: 10.2214/AJR.18.20748). Lead investigator Elizabeth H. Dibble of Brown University and colleagues retrospectively searched databases at two tertiary breast imaging centers and an office practice, focusing on 3183 screening breast US examinations performed from October 2014 to September 2016–1434 (45.1%) after DM and 1668 (52.4%) after DBT. The purpose of the study was to compare the yield of dense breast US screening after DM versus after DBT by comparing additional cancers or other findings requiring biopsy in patients with dense breasts who undergo US screening after DM or DBT

Of these 3183 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.

Of the 36 biopsies or aspirations after DM, 6 (16.7%) were malignant, and 30 (83.3%) were benign. 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 US after DM was 5/1434, or 3.5 per 1000 women screened; after DBT, the detection rate was 5/1668, or 3.0 per 1000 women screened (p = 0.9999).

Dibble concluded: “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. 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.

doi: 10.2214/AJR.18.20748