The Influence of Screening Mammography Cessation and Resumption on Breast Cancer Presentation and Treatment: A Multi-Hospital Health System Experience During the Early COVID-19 Pandemic.

Objective: To assess the impact of the coronavirus disease-2019 (COVID-19) pandemic screening restrictions on the diagnosis and treatment of breast cancer in a single health system. Materials and Methods: We performed a retrospective, cohort investigation of breast cancer patients at a multi-institution health system from March 1, 2019 to December 31, 2020 with two time periods related to the pandemic: "Early phase" (March 18 - June 7) reflecting the time of the screening mammography moratorium and "Late phase" (June 8 - December 31) to reflect the time once screening mammography resumed. 2020 was compared to 2019 to exclude potential differences from temporal or seasonal changes. Variables included demographics, COVID related-deferral, cancer specific data, method of detection, type of treatment recommended and received. Results: Fewer patients presented with a breast cancer diagnosis during Early phase 2020 when compared to any other time period. Numbers increased significantly in Late phase 2020; total numbers of patients seen in 2020 approached but did not completely reach that of 2019. When compared to other time periods, patients who presented during the moratorium on screening were younger, more likely to be black, had a higher Body Mass Index, and were more likely to have a human epidermal growth factor receptor 2 positive tumor. There was a slight increase in size of presenting tumor and node positivity, although no differences in breast or axillary surgical management were identified. Conclusion: Despite an increase in tumor size and positive nodal status seen during the screening moratorium, surgical treatment was not negatively impacted.