Digital Breast Tomosynthesis

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. For individuals who are asymptomatic and at average risk of breast cancer who receive 3D DBT with synthesized 2D mammography for screening, the evidence includes preliminary results from an RCT, prospective observational studies, and retrospective observational studies. The relevant outcomes are overall survival, disease-specific survival, and test validity. The RCT reported similar cancer detection rates but lower recall rate for DBT plus synthesized DM. Two studies found higher detection rates with 3D DBT plus synthesized 2D mammography than with DM, one study found similar detection rates with 3D DBT plus synthesized 2D mammography compared with DM, and two found similar detection rates between 3D DBT plus synthesized 2D mammography and DBT plus DM. When comparing the recall rates of 3D DBT plus synthesized 2D mammography with DM alone, a prospective study found a higher recall rate in the former, a prospective study found similar rates, while retrospective studies had mixed findings. However, the potential for overdiagnosis (ie, diagnosis of cancer that would not cause symptoms during a patient's lifetime) cannot be ascertained because of the study designs, and interval cancer rates are not yet available. The studies lack long-term follow-up to assess false-negative results. Due to limitations in the studies, it is not possible to construct a chain of evidence. The evidence is insufficient to determine the effects of the technology on health outcomes. For individuals who have abnormal findings on breast imaging or clinical exam who receive 3D DBT as an adjunct to 2D mammography for diagnosis, the evidence includes multiple observational studies and a meta-analysis. The relevant outcomes are test validity and treatment-related morbidity. There is a lack of direct evidence on the clinical utility of DBT from diagnostic trials comparing health outcomes in patients diagnosed with breast cancer using DBT vs mammography. Mixed patient populations make it difficult to draw conclusions from the available studies on the diagnostic performance of DBT. Few prospective studies have addressed whether DBT improves diagnosis when added to mammography or mammography plus ultrasonography. Also, some concerns have been raised about the classification of microcalcification clusters with DBT alone. Due to limitations in the studies on diagnostic accuracy, it is not possible to construct a chain of evidence. The evidence is insufficient to determine the effects of the technology on health outcomes. <a id="