Prognostic significance of androgen receptor expression in HER2-positive and triple-negative breast cancer.

Triple-negative breast cancer (TNBC) and HER2-positive breast cancer are more aggressive than other subtypes of breast cancer. Due to the limited number of treatment alternatives and the absence of target receptors in TNBC, and because of progression in the HER2-positive group despite targeted treatments, new treatment targets and therapeutic combinations are required. In this context, the present study aims to evaluate the prognostic importance of immunohistochemical androgen receptor (AR) expression in HER2-positive breast cancer and TNBC subtypes. AR nuclear staining density was evaluated immunohistochemically. A total of 111 operated patients with breast cancer were included in the study; 44 (39.6%) belonged to the HER2-positive breast cancer subgroup and 67 (60.4%) belonged to the TNBC subgroup. AR expression was 34.3% and 79.5% in TNBC and HER2-positive groups, respectively. The 5-year overall survival (OS) was 76% and 58% for the group with an AR-expression > 7.5% and AR-expression < 7.5%, respectively, in the TNBC subgroup (p = 0.042). In the HER2-positive patient group, the subgroups characterised by an AR-expression > 7.5% and AR-expression < 7.5% had 5-year OS rates of 57.6% and 63.5%, respectively (p = 0.91). Including the assessment of AR expression in the routine pathological examination will contribute to our understanding of the relevance of AR in the biology and prognosis of breast cancer.