Breast cancer is the most common cancer and the leading cause of cancer death in Australian women.1 Morbidity and mortality resulting from breast cancer can be reduced through early detection in population-based screening programs. BreastScreen is a joint initiative between the Australian federal and state governments, and it provides free mammographic screening for asymptomatic women from age 40. The service targets women aged 50–74 years for biennial digital mammography, and those aged 40–49 years or ≥75 years are eligible to attend on client or medical practitioner request. If indicated by personal medical or family history, screening may be offered annually.1 In 2017–2018, over 1.8 million women participated in BreastScreen Australia, a participation rate of 54.8% of the target population. The participation rate in Western Sydney was lower at 39.9%.2

When the COVID-19 pandemic emerged in early 2020, New South Wales (NSW), Australia, was subjected to varying levels of government-mandated restrictions in response to rising COVID-19 case numbers. This included temporary closure of non-urgent healthcare services, deferral of appointments, and shifts to virtual care, along with strict stay-at-home orders and travel restrictions. BreastScreen Western Sydney closed for the periods of 26 March to 4 May 2020, and 29 June to 13 October 2021.3 Outside these lockdown-associated closure periods, screening participation was further reduced by patient reluctance to seek healthcare due to concerns of COVID-19 exposure, further burdening the healthcare system, and COVID-19-related restrictions in movement around the city, which were particularly limiting in Western Sydney4.4 There was limited availability of screening, as many sites (such as those in retail locations) were closed even when the service was operational. Furthermore, reduced availability of healthcare workers, frequently deployed to conduct COVID-19-related duties, created an additional challenge to the BreastScreen service.4

Several studies predicted that a reduction in the number of breast screening episodes may translate to a reduction in the number of early-stage cancer diagnoses.1,5,6 Modelling for Australia predicted a short-term post-COVID-19 increase in cancer stage at diagnosis, reflected by increases in tumor size, nodal involvement, and high-grade tumors.6 This was also predicted in England, the broader United Kingdom, and Canada, which also experienced similar closures to their breast screening services.1,7,8 In the long-term post-pandemic period, there may be a demand for more intensive treatment for breast cancer, due to diagnostic delays, and this may be accompanied by an increase in cancer mortality. Some of these predictions have proven correct as publications emerge describing reductions in screening numbers and an increased proportion of later-stage cancers diagnosed during the pandemic.5 As the impact of COVID-19 on health services varied significantly between jurisdictions, it is important for individual districts to evaluate the real-world effect on their local area.

The aims of this study were to (1) explore the impact of the COVID-19 pandemic on breast screening, including the magnitude of the reduction in screening episodes, and changes in client demographics and imaging features of breast cancers diagnosed in 2020–2021; and (2) use this information to make recommendations for service provision during the post-pandemic recovery. No previous research has evaluated the impact of the pandemic on screening in the Australian context.

This is a retrospective descriptive cross-sectional study. Ethics approval was obtained from the Western Sydney Local Health District (WSLHD) Human Research Ethics Committee (Quality Assurance project 2206-01 NGUI) and The University of Notre Dame Australia Human Research Ethics Committee (Cross-Institutional approval 2022-095S). Approval was given by the Cancer Institute NSW, the BreastScreen data custodian, prior to the release of the data.

This retrospective study reports the effect of the COVID-19 pandemic on attendance and outcomes at a large metropolitan population breast screening service. A significant reduction in the number of clients presenting for mammographic screening during the initial phase of the COVID-19 pandemic was seen. This can be partly attributed to the closure of the screening program for six weeks in 2020 and a longer period in 2021. There was also limited capacity for several months on re-opening due to staff deployment to COVID-19 duties and the requirements for additional cleaning protocols and social distancing for clients attending for screening. In Sydney, extremely restrictive lockdowns continued intermittently through 2021. A reduction in overall screening numbers is therefore expected and is consistent with the experience of other services around the world.5 However, the magnitude of the reduction was relatively low (a 19% reduction) compared to a systematic review that found over 35 studies reporting a reduction of ≥50% related to COVID-19.5

One of the aims of this study was to examine whether the demographic mix of clients attending was different during the COVID-affected years. Younger women were less likely to attend, reflected by lower screening rates for women under age 50 and an increase in the median age in the COVID-affected years.

Related to this, attendance for first-time screeners was lower. The reasons for this are unclear, but it may be due to the assumption that the target age for screening is 50–74 years. While women can attend for free screening from age 40 on request, they do not receive a letter of invitation until age 50. Therefore, younger women may have viewed screening as non-essential during the pandemic and chosen not to attend during this time. Targeting women aged 40–50 for catch-up screening could be viewed as less urgent. The other demographic groups that showed trends towards significance, such as socioeconomic decile and country of birth, were inconsistent and did not provide concrete guidance on groups to target for catch-up screening. Notably, there was no reduction in attendance among women who spoke languages other than English. This group was particularly vulnerable during the pandemic as health messaging did not always reach diverse cultural groups. In general, they are less likely to attend for screening.2,12

International research has shown an increase in the proportion of later-stage cancers detected during COVID-affected years.5 This was not demonstrated in the present study. Rather, there was a nonsignificantly higher proportion of DCIS cases (compared to invasive cancer) in the COVID-affected years (20% and 17% pre-COVID and 17% and 24% COVID-affected, P = 0.48).

The reason for this finding is unclear, and correlation with future data on DCIS and invasive cancer diagnoses is needed to further evaluate this. There was no difference in T-stage for invasive tumors, which is not consistent with predictions of a shift to later-stage cancer during the pandemic.1

This study has some strengths and limitations. The predominant strength is the large data set that includes details of demographics, assessment data, and imaging information. The main limitation is that the data are limited to information related to the screening episode and do not include detailed surgical pathology or treatment data. Tumor size analysis was based on imaging size, and this can differ from surgical histology. Increasingly, however, imaging size is used for cases undergoing neoadjuvant chemotherapy rather than up-front surgery. The results of this study have limited generalizability because the multicultural nature of the population and the COVID-related restrictions and lockdowns are unique to the geographical area. Despite this, universal themes have emerged that make the experience relatable to different jurisdictions, particularly in Australia and countries with similar population screening programs. This study is cross-sectional, so long-term data are needed to examine the effect of the pandemic and the change in screening behavior on future cancer diagnosis and mortality.

This study demonstrated a significant reduction in screening attendance during 2020 and 2021 due to the COVID-19 pandemic. Younger women and first-time screening attendees were the groups less likely to attend during these years. This is the only demographic group that has been identified as needing focused recruitment strategies for catch-up screening. Quality indicators such as cancer detection rate and recall rate were maintained despite the challenges during this time. The observed increase in the proportion of DCIS cases, compared to invasive cancer, is of unknown clinical significance. Future evaluation to map these indicators is needed as the recovery from the pandemic continues. The service must be prepared to increase screening numbers to diagnose the cases of breast cancer that were not seen during the pandemic, and acknowledge that some of these will be later-stage at diagnosis. Close coordination with treatment services is needed, as some of these patients will present with symptomatic cancers and will not be seen through the screening program.

Ethics approval was obtained from the Western Sydney Local Health District (WSLHD) Human Research Ethics Committee (Quality Assurance project 2206-01 NGUI) and The University of Notre Dame Australia Human Research Ethics Committee (Cross-Institutional approval 2022-095S). Approval was obtained from the Cancer Institute NSW, the custodian of the BreastScreen data, prior to the release of the data.