Correlation of Ki67 Expression with Hormone Receptors, Human Epidermal Growth Factor Receptor-2 (HER-2) Status, P53 Mutation and Clinicopathological Characteristics in Pathologic Specimens of Breast Cancer Patients

Background: Breast cancer is the main cause of cancer in women and the second cause of malignancy deaths. Ki-67 is one of the molecular markers used to evaluate cancer prognosis along with other factors such as age, tumor size, lymph node involvement, estrogen receptor (ER), progesterone receptor (PR), P53, human epidermal growth factor receptor-2 (HER-2), histological and nuclear grades. This study was aimed to evaluate the correlation of KI-67 expression with some biomarkers and clinico-pathological characteristics in breast cancer patients. Materials and Methods: A total of 513 cases (all female) aged 40- 80 years, were randomly selected from patients who were admitted in two centers affiliated with Tehran University of Medical Sciences (Buo-alli and Kasra hospitals) over a 7-year period (2010-2015). Assessment of tumors for HER-2, P53, ER PR, pathological type and histologic grade was performed. Ki-67 labelling index (Ki-67LI) was defined as the percentage of MIB1-positive cells among a total number of 1,000 malignant cells at high-power magnification (×400).Results: Our study showed that age, ER and PR status were negatively correlated with Ki-67LI (P<0.05). Moreover, number of lymph nodes involved, HER-2, P53 and nuclear grades had a positive correlation with Ki-67LI (P<0.05), whereas, tumor size and histological grade showed no significant correlation with Ki-67LI (P =0.195 and P=0.721, respectively). Conclusion: Results of our study and other studies confirm that the expression of Ki-67 is significantly associated with ER, PR, HER-2 and P53 status. On the other hand, Ki-67 relationship with clinical characteristics such as age, tumor size and lymph node metastasis is not completely established and needs further research.