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.

Breast cancer screening using digital breast tomosynthesis compared to digital mammography alone for Japanese women.

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.