The Impact of the COVID-19 Pandemic on Patients with Breast Cancer, Diagnostic Delays and Disease Progression: A Retrospective Study.

[BACKGROUND] Breast cancer is the most frequent malignancy among women. The COVID-19 pandemic significantly impacted healthcare systems, potentially affecting the management of this disease. Due to the critical importance of early diagnosis and treatment, and the limited data on the pandemic's specific effects, this study aimed to determine the correlation between the COVID-19 pandemic and various breast cancer parameters.

[METHODS] This retrospective study included patients with breast cancer in Shiraz, Iran. Patients were divided into two groups, including those diagnosed before and after the start of the COVID-19 pandemic (from September 2018 to March 2021). Variables included demographic, clinical, and management features. Continuous variables were reported as mean±SD, and the categorical data were reported as frequency and percentage. The significance level was set as P<0.05.

[RESULTS] The study documented 1,435 patients: 811 patients were diagnosed before the pandemic, and 624 patients were diagnosed after. The mean initial tumor size at the time of diagnosis was significantly larger in the post-pandemic group than the pre-pandemic group (2.29±1.44 vs. 2.11±1.39 cm, respectively; P=0.001). The distribution of cancer stages also differed significantly (P=0.001). While the prevalence of stage 1 disease was similar between groups (30.1% vs. 28.9%), the prevalence of stage 2 (14.8% vs. 8.5%) and stage 3 (10.1% vs. 7.0%) was significantly higher in the post-pandemic group (Stage 1: 30.1 vs. 28.9%, Stage 2: 8.5 vs. 14.8%, Stage 3: 7 vs. 10.1%; P=0.001).

[CONCLUSION] Following the COVID-19 pandemic, patients presented with significantly larger breast tumors, increased axillary involvement, and more advanced stages after the COVID-19 pandemic.