Community-Based Breast Cancer Screening Using Digital Breast Tomosynthesis Versus Digital Mammography: Comparison of...

BACKGROUND. Prior studies comparing cancer screening by digital breast tomosynthesis (DBT) and digital mammography (DM) have largely entailed prospective trials and investigations at tertiary academic centers, which may encounter high-risk patient populations and lack heterogeneity among interpreting radiologists. Thus, results may not generalize across real-world community settings in the United States. OBJECTIVE. The purpose of this study was to compare DBT and DM in terms of screening performance and tumor characteristics of screen-detected cancers in a community practice setting. METHODS. Data were retrospectively retrieved for all screening mammography examinations performed by DBT or DM at four outpatient private practice facilities from January 1, 2012, to July 10, 2019. Examinations were interpreted by one of 26 radiologists (21 breast radiologists, five general radiologists). Further detailed information was recorded from radiology and pathology reports for all screen-detected cancers. Statistical comparisons were performed between DBT and DM in terms of screening performance and tumor characteristics of screen-detected cancers. RESULTS. A total of 310 cancers were detected in 47,096 screening DBT examinations and 83,200 screening DM examinations. Cancer detection rate was higher (p < .001) for DBT (3.4 per 1000 women) than for DM (1.8 per 1000 women). PPV1 was higher (p < .001) for DBT (3.5% [161/4641]) than for DM (2.1% [149/7116]). Patients with DBT-detected cancer were younger than those with DM-detected cancer (mean age [range], 61 years [40-87 years] vs 64 years [37-88 years]; p = .02). A greater percentage of DBT-detected than DM-detected cancers were invasive (85.1% [137/161] vs 72.5% [108/149]; p = .006), grade 1 when invasive (27.9% [38/136] vs 17.8% [19/107]; p = .04), and node negative (92.2% [71/77] vs 78.4% [58/74]; p = .02). Cancers detected by DBT and DM were not significantly different in histologic subtype, molecular subtype, or mean size (all p > .05). CONCLUSION. DBT showed a higher cancer detection rate and PPV1 than DM, and patients were younger at cancer diagnosis with DBT. Cancers detected on DBT were more often invasive, grade 1, and node negative. CLINICAL IMPACT. The findings support the generalizability of insights into DBT-based screening, which previously have been investigated primarily in academic settings.