So far, few studies have reported results from implementing tomosynthesis in breast cancer screening. These results are very promising and confirm that DBT may become the next gold standard for breast cancer screening. A brief overview of these DBT screening studies are summarized in Table 1.

The Italian Screening with Tomosynthesis OR Standard Mammography (STORM) trial recruited women ≥48 years attending the population-based screening program in Trento and Verona. Screen-reading was carried out in two sequential phases: first 2D only, and soon afterward, integrated 2D and DBT [20]. A remarkable increase in the cancer detection rate was reported: 5.3 per 1,000 women for 2D only compared with 8.1 per 1,000 screens for integrated 2D and 3D [20]. Stratified analysis revealed that integrated 2D plus 3D mammography was associated with an increased cancer detection rate in both younger and elderly age groups and both breast-density groups. Integrated 2D and 3D may have reduced false-positive callbacks by approximately 17% [20].

The Oslo Tomosynthesis Screening Trial (OTST) is a large, prospective, single-institution study that is part of the population-based Norwegian Breast Cancer Screening Program (NBCSP). This program invites women aged 50- 69 years to biennial two-view mammography. The OTST included independent double reading of 2D FFDM as well as independent double reading of combined 2D and DBT [21]. Preliminary results showed a significantly improved sensitivity, with a relative increase in cancer detection of about 30% [22]: the detection rate for FFDM alone was 6.1 cancers per 1,000 examinations compared with 8.0 cancers per 1,000 examinations for combined FFDM plus tomosynthesis [21]. The additional cancers detected using combined 2D plus 3D reading mode were invasive cancers mainly presenting as distortion and spiculated masses, whereas ductal carcinoma in situ (DCIS) detection was the same using the two reading modalities [21].

A USA observational study from a multisite community-based breast center compared performance measures at screening mammography without and with the use of digital breast tomosynthesis [23]. The cancer detection rate increased from 4.0 to 5.4 per 1,000 screening examinations using combined 2D plus 3D mode (Table 1). Interestingly, the detection of invasive cancers increased from 2.8 to 4.3 per 1,000 examinations [23]. Furthermore, a significant reduction in recall rates from 8.7% to 5.5% was found [23].

A retrospective USA study including four sites compared FFDM at sites without DBT and combined FFDM plus tomosynthesis at sites having DBT [24]. This study also applied a single reading, as is usually done in the USA. The overall recall rate revealed a significantly lower rate of 8.4% for combined 2D plus 3D mode compared with conventional FFDM alone [24]. The cancer detection rate increased from 5.2 per 1,000 patients for FFDM alone to 5.7 per 1,000 examinations for the tomosynthesis group, but this 9.5% increase in cancer detection was nonsignificant (Table 1).

The Malmø Breast Tomosynthesis Screening Trial (MBTST) [25] is a large, ongoing, single-institution trial. The estimated enrollment is 15,000 women aged 40–74 years invited to its population-based mammography screening program (Table 1). So far, only preliminary results have been presented as oral presentations at international radiological congresses.