*Article* **Reducing Unnecessary Biopsies Using Digital Breast Tomosynthesis and Ultrasound in Dense and Nondense Breasts**

**Ibrahim Hadadi 1,2,\*, Jillian Clarke 1, William Rae 1,3, Mark McEntee 1,4, Wendy Vincent 5 and Ernest Ekpo 1,6**


**Abstract:** Aim: To compare digital breast tomosynthesis (DBT) and ultrasound in women recalled for assessment after a positive screening mammogram and assess the potential for each of these tools to reduce unnecessary biopsies. Methods: This data linkage study included 538 women recalled for assessment from January 2017 to December 2019. The association between the recalled mammographic abnormalities and breast density was analysed using the chi-square independence test. Relative risks and the number of recalled cases requiring DBT and ultrasound assessment to prevent one unnecessary biopsy were compared using the McNemar test. Results: Breast density significantly influenced recall decisions (*p* < 0.001). Ultrasound showed greater potential to decrease unnecessary biopsies than DBT: in entirely fatty (21% vs. 5%; *p* = 0.04); scattered fibroglandular (23% vs. 10%; *p* = 0.003); heterogeneously dense (34% vs. 7%; *p* < 0.001) and extremely dense (39% vs. 9%; *p* < 0.001) breasts. The number of benign cases needing assessment to prevent one unnecessary biopsy was significantly lower with ultrasound than DBT in heterogeneously dense (1.8 vs. 7; *p* < 0.001) and extremely dense (1.9 vs. 5.1; *p* = 0.03) breasts. Conclusion: Women with dense breasts are more likely to be recalled for assessment and have a false-positive biopsy. Women with dense breasts benefit more from ultrasound assessment than from DBT.

**Keywords:** DBT; ultrasound; benign biopsy; breast density; breast cancer
