The impact of COVID-19 on breast cancer mortality trends in Brazil: A time-series study

Background: There is a lack of research on whether COVID-19 disruptions in breast cancer screening, diagnosis, and treatment affected mortality rates over time. Method: This ecological time series study, covering the period between 2013 and 2023, utilizes the inflection point regression model and calculates the Annual Percentage Change (APC). The study used open-access data from the Brazilian Mortality Information System. The dependent variables measured were mortality rates due to breast cancer as an underlying cause and contributing cause in women aged 20 and over. The double exponential smoothing method was applied to predict mortality rates for 2020-2023. Results: During the study period, the mortality rate due to breast cancer as a contributing cause increased approximately tenfold compared to mortality as an underlying cause (APC 6.9 % vs. 0.7 %). On average, 12 % of breast cancer-related deaths were attributed to the disease as a contributing cause. Breast cancer deaths as an underlying cause declined in 2020 and 2021, remaining below the 95 % predicted interval (95 % PI), but showed recovery until 2023. Mortality due to breast cancer as a contributing cause increased early in the pandemic, with deaths related to COVID-19 as an underlying cause comprising 39.6 % of cases in 2021. Breast cancer-related deaths, both as an underlying and contributing cause, showed an upward trend until 2021 and remained within the 95 % PI until 2023. Conclusion: During the pandemic, deaths due to breast cancer as an underlying cause decreased while contributing deaths increased, with total mortality remaining within the predicted range.