Abstract SS1-02: Racial disparities persist despite with uptake of digital breast tomosynthesis (DBT) for breast cancer screening
Authors: Ambinder Emily B , Oluyemi Eniola , Visvanathan Kala 
Published: February 2021

Abstract
Background: Breast cancer screening with digital breast tomosynthesis (DBT) has been shown to improve recall rates and detection of invasive cancer compared to 2D full field digital mammography (FFDM). The Federal Drug Administration (FDA) approved the use of DBT in 2011, and the Centers for Medicare and Medicaid Services (CMS) approved coverage in 2015. We report a single institution’s longitudinal experience of the utilization and effectiveness of DBT for breast cancer screening over time with a focus on racial differences.
Materials and Methods: The analytic population (n = 140,346) included females &gt;18 years who underwent one or more breast cancer screening examinations performed at Johns Hopkins (a tertiary care institution) and affiliated sites between 4/1/2013 and 3/30/2020. Females were categorized as having only FFDM for screening (n = 43,323) or including DBT views (n = 97,023). Recall rate and cancer detection rate were compared between the two groups overall and stratified by race using the Chi-squared test and Fishers Exact test. Univariate and multivariate logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) of having a DBT screening mammogram compared to an FFDM mammogram adjusted for year, race, and an interaction term between year and race.
Results: The mean age was 58.9 +/- 10.8 years for the FFDM group and 60.3 +/- 11.1 years for the DBT group. A larger percentage of White patients (62% FFDM vs 71.1% DBT) than Black patients (30.4% FFDM vs 22.6% DBT) or Asian patients (3.8% FFDM vs 3.0% DBT) were in the DBT group (p&lt;0.001).
During the study period, there was rapid increased in utilization of DBT. In year 1 (4/1/2013-3/30/2014), 2791/14841 (18.8%) of patients had a screening mammogram with DBT. By year 3, during which CMS approved coverage of DBT, this increased to 15069/21304 (70.7%). By year 6, 18759/20929 (90.0%) included DBT views.
All women irrespective of race had similar increases in utilization rates\ of DBT during the study period (effect modifier term OR 0.99, 95% CI 0.98-1.00). However, Black women and Asian women were significantly less likely to have a screening study with DBT compared to White women (Black women: OR 0.51, 95% CI 0.48-0.70; Asian women: OR 0.59, 95% CI 0.57-0.80).
Overall the DBT group had lower recall rate compared to the FFDM group (9.1% versus 11.2%, p&lt;0.001). This was observed for White women (8.6% vs 10.7, p&lt;0.001), Black women: 10.4% vs 11.9% p=0.001) but not Asian women (11.5% vs 11.6%, p=0.97). The DBT group also had higher cancer detection rate overall compared to the FFDM group (6.0 vs 4.1, p&lt;0.001). This was observed for White women (7.3 vs 4.5, p&lt;0.0001); Black women (7.1 vs 4.3, p=0.001), and Asian women (10.4 vs 2.6, p=0.01).
Conclusions: We observed racial differences in the utilization of DBT for screening mammography, which could have significant clinical implications given the improved recall rate and cancer detection of DBT over the study period. Longer follow up is needed to understand the impact of these racial differences. Studies are also needed to understand and address existing obstacles such as socioeconomic level, insurance status, and education to reduce the disparity preventing all patients equitable access to DBT.
Citation Format: Emily B Ambinder, Eniola Oluyemi, Kala Visvanathan. Racial disparities persist despite with uptake of digital breast tomosynthesis (DBT) for breast cancer screening [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr SS1-02.