This study aimed to investigate the effect of the COVID-19 pandemic on the clinical and pathological stages of patients diagnosed with breast cancer.

In this retrospective study, a total of 298 male and female patients over the age of 18 who were diagnosed with breast cancer and who were continuing surgical and oncologic treatment were included.

Of the 298 patients diagnosed with breast cancer, 186 (62.4%) belonged to the pre-COVID period and 112 (37.6%) to the COVID period, and there was a 39.7% decrease in the number of diagnosed patients. Statistical analyzes revealed significant differences in family history, smoking, histopathologic grade, disease stage, type of surgery performed and Cerb-B2 ovarian expression (p = 0.005, p = 0.001, p = 0.018, p = 0.035, p < 0.001, p = 0.047).

During the pandemic period, tumor size (T), axillary lymph node metastasis rate, neoadjuvant chemotherapy rate, and distant metastasis rate increased, but there was no statistically significant difference (p = 0.535, p = 0.070, p = 0.148, p = 0.153, respectively).

In pandemic situations such as COVID-19, restrictions in social life and fear of contamination can prolong the time of admission to the hospital. This may cause delays in the diagnosis of malignant diseases such as breast cancer and progression in the disease stage. In these and similar outbreaks, public awareness should be raised, and the public should be encouraged to comply with screening and follow-up programs in order to continue outpatient clinic activities and screening programs without interruption by taking contamination measures.