Impact of Covid-19 on breast cancer stage at discovery, and time to treatment in Cote d’Or, France

Due to the COVID-19 pandemic, and ensuing overcrowding in the French health system, management of patients with COVID-19 was given priority over that of patients with other pathologies, including chronic diseases. The aim of this study was to study the impact of COVID-19 on the stage of discovery of cancers diagnosed in the context of an organized breast cancer screening programme, as well as the impact on time to treatment. All women diagnosed with cancer in the Côte d'Or via organized breast cancer screening (first or second reading) from January 1, 2019 to December 31, 2020 were included in this study. Using data from pathological laboratories, clinical centers, and the breast and gynecological cancer registry of the Côte d'Or, France, we collected socio-demographic, clinical and treatment data on all patients. We compared data from the year 2019 (before-Covid) with the year 2020 (Covid). We did not observe a significant difference in the stage of breast cancer at discovery, or in time to treatment. However, the number of invasive cancers and the clinical size of in situ cancers both increased in 2020. Although these results are reassuring, continued monitoring is needed to determine the downstream effects of the pandemic.