Abstract P1-05-21: Change in breast cancer detection method, stage at diagnosis and treatment during the COVID-19 Pandemic: 2019-2021
Authors: Malmgren Judith A. , Atwood Mary , Kaplan Henry 
Published: March 2023

Abstract
Objective: Identify changes in breast cancer detection method, stage at diagnosis and treatment prior to, during and after stay-at-home orders and restricted health care access due to COVID-19.
Methods: Statistical comparison of detection method (patient (PtD), mammography (MamD) or other), Anatomic TNM Stage 8 (0-IV) and invasive BC treatment change over time by three time periods (time 1: 2019+Q1 2020; time 2: Q2-Q4 2020; time 3: 2021) using chi-square analysis in an institutional retrospective cohort of first primary breast cancer (BC) patients (n=1799), years 2019-2021.
Results: In the years prior to the study, 2016-2019, there was no difference in detection method or stage at diagnosis by year with 682 to 733 newly diagnosed BC annually (p=.462). In 2020 (n=535) and 2021 (n=582) annual diagnosed cases dropped 22% and 15% from 2019 levels. Compared to time 1, time 2 MamD BC dropped significantly (64% to 58%) with a subsequent increase in MamD BC to 70% in time 3 (p &lt; .001) creating a U-shaped curve for MamD over time. PtD BC increased in time 2 from 30% to 36% but declined in time 3 to 25% (p &lt;.001). Concurrently, stage at diagnosis shifted from time 1 to time 2 with stage 0 and I declining [stage 0: 21% to 16%, stage I: 40% to 38%] and stage II and IV increasing [stage II: 28% to 33%, stage IV: 2% to 4% stage IV] (p&lt;.001). Subsequently in 2021 stage shifted again with an increase in stage 0 to 22% and stage I to 45% and a decline in stage II (33% to 24%), III (9% to 7%) and IV (4% to 2%) (p&lt;.001). Combining stage 0 and I, the percentage of lower stage BC declined from 61% to 54% and increased to 67% in time 3 (2021) when health services became more readily accessible.
There was no change in type of surgery for invasive breast cancer (stage I-III, n=1386) with equivalent numbers of breast conserving surgery (58%), subcutaneous mastectomy (24%) and mastectomy (18%) over the time period. Chemotherapy treatment rates for invasive BC did not change (38%). Radiation therapy increased from 66% (time 1: 2019+Q1 2020) to 73% (time 2: Q2-Q4 2020) then back to 64% in time 3: 2021 (p=.007) independent of surgery type but concordant with an increase in stage IA and stage IIB BC among invasive breast cancer cases in time 2: Q2-Q4 2020 (p&lt;.001). Likewise, neoadjuvant therapy increased and then declined from 33% to 38% to 29% from time 1 to time 3 (p&lt;.001).
Conclusions: Number of diagnosed BC cases fell after the first quarter of 2020 during the time of COVID-19 related shut downs and decreased access to health services. During the Q2-Q4 2020 time period mammography detected BC declined with a relative increase in patient detected breast cancer. When mammography detection declined, BC stage at diagnosis shifted to higher stage concurrent with increased rates of radiation and neoadjuvant therapy. In 2021, the relative increase in mammography detected BC indicates a return to more normal screening patterns with a catch up for screening lost in the prior year due to access limitations. In the third time period: 2021, with the return to prior levels of mammography detected breast cancer, stage shifted back to pre-pandemic expected distribution and the excess treatment with radiation and neoadjuvant therapy declined to previously observed levels. Although the changes in detection method, stage and treatment did not persist they were statistically significant and could represent a need for re-establishing pre-pandemic screening behavior.
Table 1 Detection Method by COVID Pandemic Diagnosis Time Periods: 2019-2021 (N=1799).
Citation Format: Judith A. Malmgren, Mary Atwood, Henry Kaplan. Change in breast cancer detection method, stage at diagnosis and treatment during the COVID-19 Pandemic: 2019-2021 [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P1-05-21.