Androgen receptor is frequently expressed in HER2-positive, ER/PR-negative breast cancers

The estrogen receptor (ER)/progesterone receptor (PR)-negative breast carcinomas (BCs) encompass three molecular subtypes: one with human epidermal growth factor receptor 2 (HER) overexpression, one normal like, and the triple negative. The androgen receptor (AR) is expressed in 70–90% of invasive BCs. The aim of our study is to detect the expression of AR in a series of ER/PR-negative BCs to ascertain if there is clinical significance in relation to BC molecular subtypes. A immunohistochemical study for all receptors and cytokeratin expression was performed in 232 cases of ER/PR-negative BCs. According to cytokeratin expression, BCs were classified into two groups: luminal-type BCs (44.2%) and basal-like-type BCs (55.8%). According to the expression of HER2, 59.3% were triple-negative BCs (when ER, PR, and HER2 were negative) and 40.7% were HER2-positive BCs. AR expression was observed in 128 tumors (56.6%). One hundred and ten cases (48.8%) had >10% and 18 (7.8%) had