Immunohistochemical expression of GPR30 in breast carcinoma of Egyptian patients: an association with immunohistochemical subtypes

Breast carcinoma in Egyptian women is a biologically more aggressive disease than those diagnosed in Western women, although a substantial number of cases are hormone responsive. G protein-coupled receptor-30 (GPR30), a seven transmembrane domain protein, is currently recognized as an estrogen receptor. This study aimed at evaluating the expression of GPR30 in breast carcinomas of Egyptian patients and its association with clinicopathologic parameters and immunohistochemical subtypes of breast carcinoma. Immunohistochemical staining for GPR30 was applied on 51 archival formalin-fixed paraffin-embedded cases of invasive ductal carcinoma. Staining was assessed using a semiquantitative scoring system taking staining intensity and extent into consideration. GPR30 was observed in 33/51 (65%) of invasive ductal carcinoma cases. GPR30 was significantly associated with larger tumor size (p = 0.009), increased number of positive lymph nodes (p = 0.04), definite lymph-vascular invasion (LVI) (p = 0.002), peri-nodal invasion (p = 0.02), and the presence of coagulative tumor cell necrosis (p = 0.02). Moreover, a significant association between positive GPR30 expression and ER positivity (p = 0.02), as well as HER2/neu positivity (p = 0.03), were also observed. Most of the luminal A and B subtypes were GPR30 positive; however, all the triple negative cases were GPR30 negative (p = 0.010). GPR30 might contribute to the aggressive behavior of Egyptian breast carcinoma. Therefore, it could be useful in the therapeutic decision making in breast cancer patients.