Ki-67 expression and its correlation with clinicopathological parameters in Iraqi breast cancer patients

Breast cancer is the most common cancer worldwide and the major cause of cancer-related death among women in both developed and developing countries. In Iraq, breast cancer accounted for 37.9% of all malignant cases in 2020 and 15.3% of cancer-related fatalities. Relevant biomarkers play an important role in predicting prognosis and deciding the most effective therapy for each patient to delay metastases and reduce mortality. Objective: This study aimed to assess the significance of Ki-67 expression as a prognostic biomarker in breast cancer patients as well as investigate the correlations between Ki-67 and their clinicopathological features. Methods: The case-control study comprised sixty newly diagnosed breast cancer patients and ten women with benign breast tumors who served as controls. We assessed the tissue expression level of Ki-67 protein using the immunohistochemistry technique. Results: Our results showed that the median immunohistochemical expression scores of Ki-67 in the newly diagnosed breast cancer group were higher than those of the control group; the difference was significant (p < 0.001). The Ki-67 expression score in breast cancer cells increases with tumor size and grade. Ki-67 expression showed a substantial negative correlation with estrogen receptor expression and a significant positive correlation with HER2 expression.