Abstract
BACKGROUND: The impact of the COVID-19 pandemic on breast cancer care across Brazilian regions with varying Human Development Index (HDI) levels remains unclear. This study evaluates the pandemic's effects on screening mammograms, tumor staging at diagnosis, and treatment initiation in the Brazilian Public Health System between 2017 and 2022, focusing on regions with different HDI levels. METHODS: This ecological time series study uses an inflection point regression model and monthly percentage change (MPC) to analyze an open-access Brazilian Public Healthcare System dataset. The study focuses on trends and variations in these variables among women aged 50-69 in three state groups classified by HDI: Group A (very high), Group B (medium), and Group C (high). RESULTS: The average monthly rate of screening mammograms was highest in Group A (10.70) and lowest in Group B (8.38). At the onset of the COVID-19 pandemic, screening rates dropped significantly, with the most significant decline in Group B (58.6% decrease) and the smallest in Group A (45.7% decrease), lasting for three months. Subsequently, this variable recovered until December 2022 but was insufficient to restore the total series MPC to pre-pandemic levels. Group B had the lowest average rate of early-stage (0-II) diagnoses (2.88), while Group C had the highest (3.68). Early-stage diagnoses declined in the first three months of the pandemic, followed by a partial recovery that was insufficient to restore the pre-pandemic MPC levels. The proportion of advanced-stage diagnoses was highest in Group B (49.02%) and lowest in Group A (45.97%). The pandemic maintained the upward trend of advanced-stage (III-IV) diagnoses across all groups in the total time series. The average proportion of treatments initiated after 60 days of diagnosis was above 60% across all groups, with Group B at 64.50%. This variable began to rise 3 to 4 months after the pandemic and continued increasing until December 2022, with a greater intensity than the pre-pandemic period across all groups. CONCLUSION: The COVID-19 pandemic reduced breast cancer screening and early diagnosis in Brazil, leading to more advanced cases and treatment delays across all regions, with varying impacts according to regional HDI levels.