G-protein Coupled Estrogen Receptor 1 Expression in Primary Breast Cancers and Its Correlation with Clinicopathological Variables

PURPOSE: G-protein coupled estrogen receptor 1 (GPER) probably play important roles in the progression of breast cancer including endocrine therapeutic resistance. We evaluated GPER in primary breast cancers. METHODS: Immunohistochemistry was used to detect GPER in paraffin-embedded tissues of primary breast cancers from 423 patients and GPER expression was correlated with clinicopathological factors. RESULTS: GPER was expressed in 63.8% of specimens, coexpressed with estrogen receptor alpha (ERα) in 36.6% of tumors and was positive in 62.5% of the ERα-negative tumors. The expression of GPER had no relationship with the status of ERα, progesterone receptor and HER2. Although the expression of GPER was significantly inversely related with nodal status (p=0.045), no correlation between GPER expression and other clinicopathological variables (age, menstruation status, tumor size, stage, histologic grade, Nottingham Prognostic Index or pathological type) was found. CONCLUSION: GPER and ERα exhibited independent expression pattern of distribution in primary breast cancers. A long-term follow-up and a more definite molecular phenotype for ER are necessary in confirming studies.