Impact of COVID-19 on breast cancer care - a retrospective cohort study in Brazil

The COVID-19 pandemic disrupted healthcare systems worldwide and substantially affected breast cancer care. International reports have described delays in diagnosis, stage, and modifications in treatment strategies, however, little is known about how the pandemic has affected the entire sequence of steps from diagnosis to treatment initiation and completion within the Brazilian public healthcare system. This retrospective cohort study followed the STROBE guidelines and was conducted at a high-volume public cancer center in São Paulo, Brazil. A total of 1,306 women diagnosed with invasive or in situ breast cancer were included: 755 patients in the prepandemic period (March 2018–February 2019) and 551 patients in the pandemic period (March 2020–February 2021). Clinical, pathological, treatment, and time-related variables along the care pathway were extracted from electronic medical records and compared using appropriate statistical tests, with significance set at p < 0.05. A 32% reduction in the number of treated patients occurred during the pandemic (551 vs. 755). Patients who were diagnosed during the pandemic were younger (48.3 vs. 53.6 years; p < 0.001) and presented with more advanced clinical stages, including higher rates of cT3–T4 tumors and nodal involvement (p < 0.001). The use of neoadjuvant therapy increased from 36.8% to 49%, particularly among early-stage and luminal B tumors. Key intervals across the care pathway were significantly prolonged, including time to initial treatment and completion of adjuvant therapy. Radiotherapy practices have shifted toward hypofractionated protocols. The first year of the COVID-19 pandemic was associated with fewer treated patients, stage migration toward more advanced disease, greater reliance on neoadjuvant therapy, and prolonged time intervals along the care pathway from diagnosis to treatment initiation and completion. These findings highlight the need for resilient oncology systems, protected treatment pathways, and strengthened care coordination to mitigate the impact of future healthcare crises.