Background: The purpose of this study is to confirm the position of DBT in breast cancer screening in Japan, to assess cancer detection rates, recall rates, positive predictive value (PPV), and to evaluate the type of mammographic findings of cancer with the use of digital mammography alone (2DDM) and combined with digital breast tomosynthesis (DBT).
Methods: 11,894 examinations of the opportunistic breast cancer screening using only 2DDM and 2DDM plus DBT were performed from May 1, 2017 to March 31, 2019. The 11,894 women [3535 women who received DBT in addition to 2DDM (3D group) and 8359 who received 2DDM only (2D group)] participated in this study. The study was approved by the Institute's Ethics Committee and all participants provided written informed consent.
Results: The recall rate was 2.6% for the 3D group and 3.6% for the 2D group (p < 0.01). The cancer detection rate was 0.17% in both 3D and 2D groups (p = 0.978). The positive predictive value (PPV) was 6.5% for the 3D group and 4.7% for the 2D group (p = 0.484). The cause of the decrease in recall rate was due to a decrease in the finding of focal asymmetric density (FAD).
Conclusion: The recall rate was improved by using DBT for breast cancer screening in Japanese women. Cancer detection rates were exactly the same in DBT and 2DDM groups, so only DBT non-inferiority could be verified. We have verified that breast cancer screening combined with DBT is useful even for Japanese women to reduce unnecessary further examination.
Keywords: 3D mammography; Breast cancer screening; Digital breast tomosynthesis; Mammography.