Expression of Androgen Receptor in Breast Cancer.

Abstract

Abstract Background: Androgen receptor (AR) is one of biomarkers and its role in breast cancer is still unclear. The aim of this study was to investigate the relationship between AR expression and clinicopathological factors in breast cancer patients.Patients and Methods: AR was consecutively evaluated in 413 primary breast cancers from whole sections of surgically resected specimens using immunohistochemical staining from January 2008 to March 2009. The associations between AR expression and clinicopathological parameters were analyzed. Tumors with 10% or more nuclear stained cells were considered as positive for AR expression. The differences between variables were calculated by chi-square test and Fisher's exact test was used when appropriate.Results: The median age at diagnosis was 49 years (range, 26-84). AR was found in 72.7% (48/66) of in-situ carcinoma and in 72.9% (253/347) of invasive carcinoma. Overall expression rates of AR were 72.9%, which were higher than those of ER and PR expression, 68.5% and 62.0%, respectively. AR was significantly expressed in patients with no elevated preoperative serum cancer antigen 15-3 (CA 15-3) levels (p = .042), smaller tumor size (p = .035), lower histologic grade (p < .001), ER-positive (p < .001), progesterone receptor-positive (p < .001), and non-triple-negative breast cancer (p < .001). Metaplastic, medullary, and mucinous types carcinomas showed less AR expression (p = .030). Although it was statistically not significant, patients with younger age (≤ 35 years), axillary lymph node involvements, and higher stage showed higher rates of AR negativity. In ER-negative tumors, AR expression was significantly correlated with HER-2 over-expression (p < .001). In ER-positive tumors, however, there was no relationship between AR expression and HER-2 over-expression (p > .05).Conclusions: AR is expressed in a significant number of breast cancers and is associated with favorable tumor differentiation and smaller tumor size. These results might suggest that AR may be an independent prognostic factor in breast cancer. AR may also be associated with growth factor signaling and be useful therapeutic target in ER-negative tumors. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 4156.