Abstract P3-10-03: The Implication of Androgen Receptor Expression in Breast Cancers

Abstract

Abstract Purpose: To evaluate the implication of androgen receptor (AR) expression in patients with breast cancer. Methods: Immunohistochemically AR expression was investigated in 931 invasive breast cancers prepared in tissue microarray blocks that were collected in between November 1999 and August 2005. The clinicopathological features, disease-free (DFS) and overall survival (OS) were analyzed using chi-square test, Kaplan-Meier methods, and Cox's models. Tumors with ≥10% nuclear-stained cells were considered to be positive for AR, estrogen receptor (ER), and progesterone receptor (PR) expression and 3+ with immunohistochemical staing or FISH + were considered positive for HER2 expression. Results: The positive expression of AR, ER, PR, and HER2 was 58.1%, 72.2%, 61.4%, and 24.7% of all patients, respectively. AR expression was significantly associated with an older age at diagnosis (p=0.007), smaller tumor size (P<0.001), well differentiation (P<0.001), higher hormone receptors expression (P<0.001), non-triple-negative breast cancers (non-TNBC) (P<0.001), and lower proliferation index (P<0.001). In ER-negative cancers, AR expression was associated with well differentiation, lower Ki-67 index, and distinctively HER2 overexpression. With median follow-up duration of 72.7 months, AR was significantly associated with better DFS (p=0.023) and OS (p=0.048) and the association was same in ER-positive cancers but was disappeared in ER-negative cancers. In Cox's models, AR expression was an independent prognostic factor for DFS (hazard ratio, 0.654; p=0.049), but it did not reach a statistical significance for OS (hazard ratio, 0.647; p=0.119) even in ER-positive tumors. Interestingly, tumors with molecular apocrine features (ER-negative, AR-positive, and HER2-positive) showed a trend of poorer outcome with AR expression, but there was no impact of AR expression on the survival in 156 patients with TNBC. Conclusions: AR expression is significantly associated with favorable clinicopathological features and better outcomes in ER-positive cancers but tumors with molecular apocrine features showed a trend of poorer outcome with AR expression. These results suggest that AR expression could be an additional marker for endocrine responsiveness in ER-positive tumors and a target molecule for the molecular apocrine tumors. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P3-10-03.