Effect of COVID-19 NHS breast screening pause on breast cancer presentation and management: an insight into overdiagnosis

Objective To ascertain the impact of a 3-month pause in the NHS Breast Screening Programme (NHSBSP) during COVID-19 on numbers, characteristics and outcomes of breast cancer patients Design We compared numbers, referral sources (NHSBSP/GP), tumour characteristics, treatments, and survival before and during COVID-19 using chi-square tests and Kaplan-Meier estimates. Patients were grouped into: (a) all cases from 2019 to 2021 ( n = 3353) and (b) six selected months in 2019 and 2020 ( n = 325). Setting The study was conducted with the breast units of two large London NHS hospitals as a local audit to understand the impact of COVID-19 on breast cancer management. Participants Patients diagnosed with breast cancer from 2019 to 2021 were analysed. Main outcome measures Temporal variation in the number of breast cancer cases by referral source and the impact of the pause in screening mammography due to the COVID-19 pandemic on changes in tumour characteristics, treatments and survival. Results Overall, there were 31% fewer patients in 2020 vs. 2019 (886 vs. 1281, p = .002), due to fewer screen-detected (851 vs. 398) rather than symptomatic cases (432 vs. 459), p < .00001), with no corresponding increase in 2021 ( n = 1186) In the detailed analysis, there were significantly fewer grade 1 cancers (11/120 vs. 37/204, p = .028) in 2020 vs. 2019, but there was no stage shift from smaller or less advanced (node-negative) tumours to larger or more advanced tumours, and no difference in extent of surgery, i.e., ratios of breast conservation to mastectomy, or sentinel node biopsy to axillary clearance. There was no difference in time from referral to diagnosis between the two time periods. The median follow-up was 3.8 years; K-M survival curves overlapped, with no difference in 3-year survival (90.5% vs. 91.7%, HR=1.09, p = .83). Conclusions During the COVID-19-induced NHSBSP pause, good-prognosis (grade 1) cancers reduced without an increase in larger, or node-positive cancers, or more extensive surgery, and 3-year survival remained unchanged, suggesting that pausing NHSBSP may have avoided overdiagnosis without causing harm.