Expression of Androgen Receptor in Triple-Negative Breast Carcinomas and Inflammatory Breast Carcinomas
Yun Gong, Wei Wei, Yun Wu, Lei Huo. University of Texas MD Anderson Cancer Center, Houston, TX
Background: Androgen receptor (AR) is commonly expressed in breast cancers and has been implicated in breast cancer biology. Triple-negative breast carcinoma (TNBC) and inflammatory breast cancer (IBC) both have generally aggressive clinical course and either do not benefit from or frequently develop resistance to conventional targeted therapies. We herein sought to examine the prevalence of AR expression and explore its value as a prognostic marker and a potential therapeutic target in these two subgroups of breast carcinoma.
Design: Tissue microarrays of 91 TNBCs (between 6/2005 and 11/2011) and 88 inflammatory breast carcinomas (between 9/1994 and 8/2004) were stained with monoclonal antibody AR441 (dilution 1:30, DAKO) by immunohistochemistry. Nuclear staining in greater than 10% of invasive tumor cells was defined as positive. Correlations between AR expression and pathologic parameters, biomarkers (Fisher's exact test) and between AR expression and overall survival (OS) (log-rank test) were examined.
Results: The median follow-up and 5-year OS rate were 5.7 years and 63%, respectively, for TNBC and 10.8 years and 46%, respectively, for IBC. AR was positive in 17% of TNBCs and 39% of IBCs. Positive AR expression was significantly associated with lymphovascular invasion in both tumor subgroups (p = 0.02 and p = 0.01, respectively). There was no significant association between AR positivity and Ki67 expression, other pathologic parameters or OS in either subgroup. There was no significant association between AR positivity and ER, PR and HER2 status in IBCs. In the IBC subgroup, patients with AR-/ER- tumor had a significantly worse OS than those with AR-/ER+, AR+/ER- or AR+/ER+ tumors (p = 0.03).
Conclusions: Positive AR expression was found in 17% TNBC and 39% of IBC. The IBC patients with AR-/ER- tumor had a significant worse OS than IBC patients with other combinations of AR/ER expression. Perplexingly, AR positivity was significantly associated with lymphovascular invasion in both TNBC and IBC subgroups. Further study with larger series is required to delineate the biologic mechanism of AR in these tumors.
Tuesday, March 5, 2013 9:30 AM
Poster Session III # 7, Tuesday Morning