Breast cancer screening with tomosynthesis (3D mammography) with acquired or synthetic 2D mammography compared with 2D mammography alone (STORM-2): a population-based prospective study

Bernardi D. et al. The Lancet Oncology. 2016 Aug;17(8):1105-1113

Background
Breast tomosynthesis (pseudo-3D mammography) improves breast cancer detection when added to 2D mammography. In this study, we examined whether integrating 3D mammography with either standard 2D mammography acquisitions or with synthetic 2D images (reconstructed from 3D mammography) would detect more cases of breast cancer than 2D mammography alone, to potentially reduce the radiation burden from the combination of 2D plus 3D acquisitions.

Findings
Between May 31, 2013, and May 29, 2015, 10 255 women were invited to participate, of whom 9672 agreed to participate and were screened. In these 9672 participants (median age 58 years [IQR 53-63]), screening detected 90 cases of breast cancer, including 74 invasive breast cancers, in 85 women (five women had bilateral breast cancer). To account for these bilateral cancers in cancer detection rate estimates, the number of screens used for analysis was 9677. Both 2D-3D mammography (cancer detection rate 8.5 per 1000 screens [82 cancers detected in 9677 screens]; 95% CI 6.7-10.5) and 2D synthetic-3D mammography (8.8 per 1000 [85 in 9677]; 7.0-10.8) had significantly higher rates of breast cancer detection than 2D mammography alone (6.3 per 1000 [61 in 9677], 4.8-8.1; p<0.0001 for both comparisons). The cancer detection rate did not differ significantly between 2D-3D mammography and 2D synthetic-3D mammography (p=0.58). Compared with 2D mammography alone, the incremental cancer detection rate from 2D-3D mammography was 2.2 per 1000 screens (95% CI 1.2-3.3) and that from 2D synthetic-3D mammography was 2.5 per 1000 (1.4-3.8). Compared with the proportion of false-positive recalls from 2D mammography alone (328 of 9587 participants not found to have cancer at assessment) [3.42%; 95% CI 3.07-3.80]), false-positive recall was significantly higher for 2D-3D mammography (381 of 9587 [3.97%; 3.59-4.38], p=0.00063) and for 2D synthetic-3D mammography (427 of 9587 [4.45%; 4.05-4.89], p<0.0001). Interpretation
Integration of 3D mammography (2D-3D or 2D synthetic-3D) detected more cases of breast cancer than 2D mammography alone, but increased the percentage of false-positive recalls in sequential screen-reading. These results should be considered in the context of the trade-off between benefits and harms inherent in population breast cancer screening, including that significantly increased breast cancer detection from integrating 3D mammography into screening has the potential to augment screening benefit and also possibly
contribute to overdiagnosis.