The analysis of HER-2 protein level and clinicopathological features of breast cancer demonstrated that HER-2 expression and HER-2 mRNA level were not associated with the age, menstrual condition, and tumor size of patients with breast cancer (all P>0.05), but was correlated with the pathological type, TNM staging, histological grade, blood vessel invasion, SLN metastasis, and expression levels of ER and PR (all P<0.05) (Table 2). This evidence concerns the gene ESR1 and breast cancer.