Ki-67 expression and significance of different molecular subtypes of breast invasive ductal carcinoma

Abstract

To analyze Ki-67 expression and explore its significance in different molecular subtypes of breast invasive ductal carcinoma (IDC). The expressions of estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor-2 (HER-2) and Ki-67 were detected in 126 cases of IDC by immunohistochemical staining. Then the molecular subtype of each case of IDC was determined.Statistical analysis was performed to determine the relationship between Ki-67 expression and the molecular subtypes with clinicopathological features of IDC. There was no statistically significant difference of Ki-67 expression in age and tumor size (P > 0.05).However, significant difference existed in histological grading and lymph node metastasis (P < 0.05). The expression level of Ki-67 was negatively correlated with ER expression (r = -0.273, P = 0.002) and PR expression (r = -0.242, P = 0.007) and positively with HER-2 expression (r = 0.245, P = 0.006) . A low expression of Ki-67 was in LumianlA subtype (17/17) and high expression in other molecular subtypes. Moreover, the rate of high expression (Ki-67 LI>50%) in each subtype progressively increased with the degree of molecular typing and Ki-67 expression in different molecular subtypes showed significant difference (P < 0.05). The expression level of Ki-67 is correlated with histological grading and molecular type of IDC. High expression of Ki-67 carries poor prognosis. Thus it is necessary to perform a variety of routine clinicopathological examinations, such as Ki-67, ER, PR and HER-2.