Breast Cancer Screening with Digital Breast Tomosynthesis: Are Initial Benefits Sustained?

Background Performance metrics with digital breast tomosynthesis (DBT) are based on early experiences. There is limited research on whether the benefits of DBT are sustained. Purpose To determine whether improved screening performance metrics with DBT are sustained over time at the population level and after the first screening round at the individual level. Materials and Methods A retrospective review was conducted of screening mammograms that had been obtained before DBT implementation (March 2008 to February 2011, two-dimensional digital mammography [DM] group) and for 5 years after implementation (January 2013 to December 2017, DBT1-DBT5 groups, respectively). Patients who underwent DBT were also categorized according to the number of previous DBT examinations they had undergone. Performance metrics were compared between DM and DBT groups and between patients with no previous DBT examinations and those with at least one prior DBT examination by using multivariable logistic regression models. Results The DM group consisted of 99 582 DM examinations in 55 086 women (mean age, 57.3 years ± 11.6 [standard deviation]). The DBT group consisted of 205 048 examinations in 76 276 women (mean age, 58.2 years ± 11.2). There were no differences in the cancer detection rate (CDR) between DM and DBT groups (4.6-5.8 per 1000 examinations, P = .08 to P = .95). The highest CDR was observed with a woman's first DBT examination (6.1 per 1000 examinations vs 4.4-5.7 per 1000 examinations with at least one prior DBT examination, P = .001 to P = .054). Compared with the DM group, the DBT1 group had a lower abnormal interpretation rate (AIR) (adjusted odds ratio [AOR], 0.85; P < .001), which remained reduced in the DBT2, DBT3, and DBT5 groups (P < .001 to P = .02). The reduction in AIR was also sustained after the first examination (P < .001 to P = .002). Compared with the DM group, the DBT1 group had a higher specificity (AOR, 1.20; P < .001), which remained increased in DBT2, DBT3, and DBT5 groups (P < .001 to P = .004). The increase in specificity was also sustained after the first examination (P < .001 to P = .01). Conclusion The benefits of reduced false-positive examinations and higher specificity with screening tomosynthesis were sustained after the first screening round at the individual level. © RSNA, 2020 See also the editorial by Taourel in this issue.