Ki-67 expression as an indicator of invasiveness in patients with breast cancer

Background: Tumor markers have a key role in guiding breast cancer management protocols and predicting prognosis. Objective: The aim of the study is to explore the role of Ki-67 expression in breast cancer and correlate it to well-known indicators of invasiveness such as age, tumor size, grade, hormonal receptors, and lymph nodes involvement. Materials and Methods: This retrospective study was conducted on (214) patients who were newly diagnosed with breast cancer and referred to Azadi Teaching Hospital/Duhok-Iraq, from November 1st, 2016, to October 31st, 2017. Data regarding patient's demographics, tumor size, histological type and grade, nuclear grade, and lymph node involvement were obtained from medical records. Patients underwent either mastectomy with axillary lymph node dissection or breast conservation surgery. Collected specimens were sent for histopathological examination and immunohistochemistry assessments of estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor 2 (HER2), and Ki67 expressions. Results: Our study showed that histological grade, nuclear grade, mitotic index, and HER2 status were positively correlated to Ki67 index (P < 0.05). Furthermore, ER and PR status showed a negative correlation to Ki67 index (P < 0.05). Age, tumor size, and the number of lymph nodes involved displayed no significant correlation to Ki67 level (P = 0.080, 0.738, and 0.888), respectively. Conclusion: Results of this study confirmed that Ki67 index are significantly correlated with tumor grade, ER, PR, and HER2 status. However, Ki67 expression association with other clinic-pathological parameters such as age, tumor size, or lymph node involvement is not recognized and requires further studies