Comparing Screening Outcomes for Digital Breast Tomosynthesis and Digital Mammography by Automated Breast Density in a Randomized Controlled Trial: Results from the To-Be Trial
Repository for the article "Comparing Screening Outcomes for Digital Breast Tomosynthesis and Digital Mammography by Automated Breast Density in a Randomized Controlled Trial: Results from the To-Be Trial"
All analyses were performed in Stata MP 16 and the syntax can be read in the file "Analyses.do". Questions regarding this project can be directed to the corresponding author Prof. Solveig Hofvind at [email protected].
https://doi.org/10.1148/radiol.2020201150
Digital breast tomosynthesis (DBT) is considered superior to digital mammography (DM) for women with dense breasts.
To identify differences in screening outcomes, including rates of recall, false-positive (FP) findings, biopsy, cancer detection rate, positive predictive value of recalls and biopsies, and histopathologic tumor characteristics by density using DBT combined with two-dimensional synthetic mammography (SM) (hereafter, DBT+SM) versus DM.
This randomized controlled trial comparing DBT+SM and DM was performed in Bergen as part of BreastScreen Norway, 2016–2017. Automated software measured density (Volpara Density Grade [VDG] 1–4). The outcomes were compared for DBT+SM versus DM by VDG in descriptive analyses. A stratified log-binomial regression model was used to estimate relative risk of outcomes in subgroups by screening technique.
Data included 28 749 women, 14 380 of whom were screened with DBT+SM and 14 369 of whom were screened with DM (both groups: median age, 59 years; interquartile range [IQR], 54–64 years). The recall rate was lower for women screened with DBT+SM versus those screened with DM for VDG 1 (2.1% [81 of 3929] vs 3.3% [106 of 3212]; P = .001) and VDG 2 (3.2% [200 of 6216] vs 4.3% [267 of 6280]; P = .002). For DBT+SM, adjusted relative risk of recall (VDG 2: 1.8; P , .001; VDG 3: 2.4; P , .001; VDG 4: 1.8; P = .02) and screen-detected breast cancer (VDG 2: 2.4; P = .004; VDG 3: 2.8; P = .01; VDG 4: 2.8; P = .05) increased with VDG, whereas no differences were observed for DM (relative risk of recall for VDG 2: 1.3; P = .06; VDG 3: 1.1; P = .41; VDG 4: 1.1; P = .71; and relative risk of screen-detected breast cancer for VDG 2: 1.7; P = .13; VDG 3: 2.1; P = .06; VDG 4: 2.2; P = .15).
Screening with digital breast tomosynthesis combined with synthetic two-dimensional mammograms (DBT+SM) versus digital mammography (DM) yielded lower recall rates for women with Volpara Density Grade (VDG) 1 and VDG 2. Adjusted relative risk of recall and screen-detected breast cancer increased with denser breasts for DBT+SM but not for DM.