Impacts of the COVID-19 pandemic on the breast cancer control pathway in Ireland

BACKGROUND: The COVID-19 pandemic caused unprecedented disruption to healthcare services worldwide including cancer services. The aim of this study is to assess the impact of the COVID-19 pandemic on aspects of the breast cancer control pathway in Ireland, including case counts, method of presentation, stage distribution, and treatment. METHODS: Analyses used data from the National Cancer Registry Ireland available as of April 2023. For assessments of case counts, 2020 data was compared to ‘expected’ case counts projected from a Joinpoint regression model of the last stable trend in breast cancer cases up to 2019. For assessments of method of presentation, stage distribution, and treatment, 2020 data was compared to equivalent 2019 data. RESULTS: There was a 23% reduction in number of breast cancer cases diagnosed in in Ireland in 2020 than expected from pre-2020 trends. Comparing methods of presentation, screen-detected tumours showed the largest reduction from 2019 to 2010. There was comparatively little change in numbers of breast cancers presenting through symptoms. Comparing cancer stage from 2019 to 2020, there was a significantly larger reduction in pT1 tumours than in pT2, or pT2-3, or pT2-4 tumours. Similarly, there was a larger reduction in Stage I than in any other stage and in Grade 1 than in Grade 2 or Grade 2-4 cancers. Investigation of breast cancer treatment showed a small reduction in the percentage of cases treated by surgery and by radiotherapy but no apparent change in the percentage of cases receiving chemotherapy/immunotherapy. CONCLUSIONS: Patient behavioural changes, pauses in screening, and restricted healthcare access as a result of COVID-19 likely contributed to the observed reductions in case counts and screen-detection of breast cancer. The reduction in early stage breast cancers in 2020 is likely also related to screening disruption. Treatment modes may have been altered during the pandemic to reduce infection risk to cancer patient in hospitals. KEY MESSAGES: • The COVID-19 pandemic caused disruption to the breast cancer control pathway in Ireland. • Case counts and screen-detection of breast cancer as well as the proportion of early stage breast cancers diagnosed were reduced in Ireland in 2020.