Assessing breast cancer screening results through the lens of COVID-19 pandemic.

Abstract

e22507 Background: In January, 2020 World Health Organization (WHO) declared the COVID-19 outbreak as the first global health emergency. Lockdowns and restrictive procedures with the full and partial cancellation of preventive measures, including breast cancer (BC) screening, took place in Kazakhstan in 2020-2021. Purpose of this study: to determine the impact of the COVID-19 pandemic on BC screening results. Methods: The main screening indicators before (2018-2019) and during the COVID-19 pandemic (2020-2021) were studied: planned coverage and number of examined patients, the proportion of BI-RADS categories (where BI-RADS categories 4-5 are accepted as suspicious for malignancy, additional imaging by ultrasound and/or mammography followed biopsy is recommended), the number of detected cancer cases, the stage of the disease according to the screening database and the Electronic Cancer Registry. Results: 1,624,667 women underwent BC screening in 2018-2019 (96.2% of the planned amount of 1,688,829 women). 1,532,591 (79.4%) women were examined in 2020-2021, though the planned amount was 1,930,515. Before the epidemic, 23,296 patients received BI-RADS categories 4-5 (1.43% from examined women) and were referred for additional ultrasound and mammography examination, in 2020-2021 – 25,008 women (1.63%). 74.2% (1,205,094 women) had BI-RADS category 1 in 2018-2019 and 63.4% (971,754 patients) – during the pandemic. In 2018-2019 - 3,377 BC cases were detected (cancer detection rate was 2.0 per 1000 investigations). In 2020-2021 - 2,474 BC cases were identified (cancer detection rate 1.6 per 1000 investigations). Proportion of screen-detected cancers in stage 0-I was 45.1% in 2018-2019 and 47.5% in 2020-2021. During the pandemic, the number of participants who underwent BC screening significantly decreased (by 20.6% of the planned). The level of cancer detection decreased too (by 22.8%). There was an increase in patients requiring further examination (BI-RADS categories 4-5) and decrease the number women with BI-RADS 1. With an increase in indications for additional ultrasound and radiological examination, the number of revealed cancers reduced by 1.5 times (in 2018-2019, 14.5% patients with BI-RADS categories 4-5 had BC confirmed, in 2020-2021 – only 9.9%). Conclusions: BC screening has been significantly reduced during the COVID-19 pandemic. At the same time, attention should be paid to the increase in overdiagnosis of mammographic pathology, possibly due to an increase in the density of breast tissue on the background of nonspecific inflammation accompanied by lymphadenopathy. The impact of COVID-19 on BC is still unknown. Further research will be needed to confirm the link between COVID-19 and mammography picture and BC.