Purpose: To compare benchmark screening outcomes of recall rates (RCR), cancer detection rates/1000 women screened (CDR) and positive predictive values for recall (PPV1) in two cohorts of intermediate risk women screened with two-dimensional (2D) digital mammography (DM) and 2D-DM with digital breast tomosynthesis (DBT) in a Canadian a provincial organized annual breast cancer screening program at a community-based institution.
Materials and Methods: Retrospective review of all intermediate risk women, aged 50 years and older screened annually in the Ontario Breast Screening Program at a single community-based institution between June 2015 and May 2023. Two cohorts were compared including 2198 2D-DM examinations performed from June 2015 to March 2019, and 2163 2D-DM+DBT performed from April 2019 to May 2023. 2D-DM+DBT was performed year one, subsequent screens were synthetic 2D (s2D)+DBT. One of 13 radiologists interpreted the mammograms as a single reader. RCRs, CDRs and PPV1s were calculated for each cohort. Statistical significance of difference and 95% confidence intervals (CI) were evaluated with standard 2-proportions tests.
Results: 18 cancers were detected in the 2D-DM and 21 in the 2D+DBT cohorts. There was a trend to increase the CDR and a significant increase in RCR after the addition of DBT (CDR: 9.7 women with 2D+DBT vs 8.1 with 2D-DM, p=0.297, CI [-4.07, 7.11]; RCR: 11.7% with 2D+DBT vs 9.5% with 2D-DM, p=0.008, CI [0.0, 0.04]). PPV1 remained unchanged (PPV1: 8.3% with 2D+DBT vs 8.1% with 2D-DM, p=0.553, CI [-0.05, 0.05]).
Conclusion: There was a trend to an improved CDR, increasing the RCR without affecting the PPV1 after adding DBT to 2D mammography at a community practice in an annual intermediate risk Canadian provincial organized screening program that utilizes 2D-DM.
Clinical Relevance Statement: This study demonstrated a trend to improve CDR by adding DBT to 2D-DM, to mammographically screen intermediate risk women 50 years and older at a community-based institution in an annual organized provincial program that utilizes 2D-DM. The results could be relevant to provincial government screening guidelines and policies.
