Digital breast tomosynthesis (DBT) uses modified digital mammography (DM) equipment to obtain additional radiographic data that are used to reconstruct cross-sectional «slices» of breast tissue. Tomosynthesis may improve the accuracy of DM by reducing distortions caused by overlapping tissue. Tomosynthesis typically involves additional imaging time and radiation exposure, although recent improvements may change this.
For individuals who are asymptomatic and at average risk of breast cancer who receive 3-dimensional (3D) DBT as an adjunct to 2-dimensional (2D) mammography for screening, the evidence includes results from randomized controlled trials (RCTs), prospective observational studies, and retrospective observational studies. The relevant outcomes are overall survival, disease-specific survival, and test validity. There is a lack of direct evidence on the clinical utility of DBT from trials comparing health outcomes in patients screened using DBT and mammography. The available studies have provided limited data on interval cancers and follow-up of negative findings; however, available evidence would suggest that adding breast tomosynthesis to mammography may increase sensitivity and specificity of screening, potentially reducing the number of women who are recalled unnecessarily. Many studies had methodologic limitations, including inadequate follow-up of women with negative screening results, use of historical controls, and were based on screening practices in Europe that differ from those in the U.S. Preliminary results from the RETomo RCT would suggest an almost 90% increase in detection rate for mammography plus DBT compared with mammography alone with more instances of ductal carcinoma in situ with mammography plus DBT (+1 per 1000), benign lesions (+1 per 1000), and invasive cancers (+3 per 1000). The evidence is insufficient to determine the effects of the technology on health outcomes.
