Methods: This multicentre study recruited 446 patients from UK breast clinics. Participants underwent both standard FFDM and DBT. A blinded retrospective multi-reader study involving twelve readers and 300 mammograms (152 malignant and 148 benign cases) was conducted.
Results: Sensitivity for cancer was 86.6% with FFDM (95% CI: 85.2-88.0%), 89.1% with DBT (95% CI: 88.2-90%), and 91.7% with FFDM+DBT (95% CI: 90.7-92.6%). In the densest breasts, the maximum sensitivity increment with FFDM+DBT over FFDM alone was 10.3%, varying by density measurement method. Overall specificity was 81.4% with FFDM (95% CI: 80.5-82.3%), 84.6% with DBT (95% CI: 83.9-85.3%), and 79.6% with FFDM+DBT (95% CI: 79.0-80.2%). No differences were detected in accuracy of tumour measurement in unifocal cases.
Conclusions: Where available, DBT merits first-line use in the under 60 age group in symptomatic breast clinics, particularly in women known to have very dense breasts.
Advances in knowledge: This study is one of very few to address the accuracy of digital breast tomosynthesis in symptomatic rather than screening patients. It quantifies the diagnostic gains of DBT in direct comparison with standard digital mammography, supporting informed decisions on appropriate use of DBT in this population.