The impact of the COVID-19 pandemic on breast cancer screening and diagnosis in a Brazilian metropolitan area.

Objectives: To evaluate the performance of breast cancer screening and early diagnosis during the pandemic, compared to the pre-pandemic period.Setting: The public referral centre for screening in Campinas, São Paulo State, Brazil.

Methods: This is an audit study of performance screening and diagnostic indicators. Two periods were analysed: 2019, the pre-COVID period, and 2020, the COVID period. All women who underwent mammography in these periods were included. Indicators were compared between periods, and the US Breast Cancer Surveillance Consortium benchmarks were used as a reference.

Results: A comparison between the periods shows a reduction of 57.4% in screening and 4.4% in diagnosis using mammography. Cancer detection rate per 1000 screening mammograms dropped from 4.62 to 2.83 (p  =  0.031), while it increased from 84.43 to 89.36 in diagnosis mammograms (p  =  0.701), higher than the reference (34.4, p < 0.001). With regard to diagnosis, the proportion of minimal cancers was reduced (p  =  0.005) and was lower than the reference (40.0%, p < 0.001), along with the proportion of node-negative invasive cancers (p < 0.001). The mean size of invasive tumours was similar in the two periods (32.50 mm and 33.40 mm, p  =  0.808) but larger than the reference value (16.50 mm, p < 0.001). Recall rate was lower in the COVID period (22.55% vs. 27.37%, p  =  0.015).

Conclusion: The COVID pandemic caused an overall decrease in breast screening and detection of breast cancer cases, although the reduction in number of diagnosis mammograms performed was minimal. Tumour mean size was large in both periods, the pandemic highlighting a previous profile of detection at an advanced stage.