Frequency and Outcomes of BI-RADS Category 3 Assessments in Patients With a Personal History of Breast Cancer: Full-Field Digital Mammography Versus Digital Breast Tomosynthesis.

Studies establishing the validity of BI-RADS category 3 excluded patients with personal history of breast cancer (PHBC). Utilization of category 3 in patients with PHBC may be impacted not only by this population's increased breast cancer risk, but also by adoption of digital breast tomosynthesis (DBT) over full-field digital mammography (FFDM). To compare the frequency, outcomes, and additional characteristics of BI-RADS category 3 assessments between FFDM and DBT in patients with PHBC. This retrospective study included 14,845 mammograms in 10,118 patients (mean age, 61.8 years) with PHBC, who had undergone mastectomy and/or lumpectomy. Of these, 8,422 examinations were performed by FFDM from October 2014 to September 2016, and 6423 examinations by FFDM with DBT from February 2017 to December 2018, following interval conversion of the center's mammography units. Information was extracted from the EHR and radiology reports. FFDM and DBT groups were compared in the entire sample and among index category 3 lesions (i.e., earliest category 3 assessment per lesion). Frequency of category 3 assessment was lower for DBT than FFDM (5.6% vs 6.4%; p=.05). DBT, compared with FFDM, showed lower malignancy rate for category 3 lesions (1.8% vs 5.0%; p=.04), higher malignancy rate for category 4 lesions (32.0% vs 23.2%; p=.03), and no difference in malignancy rate for category 5 lesions (100.0% vs 75.0%; p=.02). Analysis of index category 3 lesions included 438 and 274 lesions for FFDM and DBT, respectively. For category 3 lesions, DBT, compared with FFDM, showed lower PPV3 (13.9% vs 36.1%; p=.02), and more frequent mammographic finding type of mass (33.2% vs 23.1%, p=.003). Malignancy rate for category 3 lesions in patients with PHBC was less than the accepted limit (2%) for DBT (1.8%), but not FFDM (5.0%). Lower malignancy rate for category 3 lesions but higher malignancy rate for category 4 lesions for DBT supports more appropriate application of category 3 assessment in patients with PHBC through use of DBT. These insights may help establish whether category 3 assessments in patients with PHBC are within benchmarks for early detection of second cancers and reduction of benign biopsies.