Comparative study of the usefulness of adjunctive tomosynthesis in breast cancer screening by mammography and ultrasound in Japan.

Introduction: There are few studies have conducted digital breast tomosynthesis (DBT) in addition to digital mammography (2DDM) and ultrasound (US) for screening. The purpose of this study is to determine the possibility of synergistic effects of DBT and US screening for Japanese.
Methods: 5023 examinations of the opportunistic screening using 2DDM and US (2D group: 2581) or 2DDM and US plus DBT (3 group: 2442) were performed at our facility from May 1, 2017 to March 31, 2019. This study was not RCT, and the backgrounds of the two groups were different.
Results: The recall rate was 3.1% in the 2D group and 2.6% for the 3D group (p = 0.27). The number of detected cancer cases was 6 (0.23%) in the 2D group and 12 (0.49%) in the 3D group (p = 0.16). The positive predictive value (PPV) was 7.4% for the 2D group and 19.0% for the 3D group (p = 0.045). There was one invasive ductal carcinoma case which had no findings in 2DDM and US, but had a slight distortion in the images of DBT.
Conclusion: We examined and reported whether DBT was useful for breast cancer screening combined with mammography and US. Compared to the 2D group, the 3D group showed better results of PPV with significant difference. However, due to the non-randomized design and difference between the two groups, the results should be interpreted in caution. Adding DBT in 2DDM and US screening would be acceptable only if the benefits and disadvantages are explained to the women undergoing the screening.
(© 2022. The Author(s), under exclusive licence to The Japanese Breast Cancer Society.)