Abstract P6-05-02: Endocrine biomarkers in response to AR-inhibition with bicalutamide for the treatment of AR(+), ER/PR(−) metastatic breast cancer (MBC) (TBCRC011)

Expression of androgen receptor in inflammatory breast cancer and its clinical relevance

BACKGROUND

Inflammatory breast cancer (IBC) is characterized by an aggressive clinical course with early metastasis and frequent resistance to conventional therapies. Identifying a novel therapeutic approach may improve the prognosis for patients with IBC. Because androgen receptor (AR)-expressing tumors may be targeted by anti-AR therapy, the authors examined the prevalence of AR expression in IBC tumors and explored its clinical relevance.

METHODS

Tissue microarrays of 88 IBC tumors were stained immunohistochemically with monoclonal antibody against AR, and the results were correlated with clinicopathologic parameters and survival outcomes.

RESULTS

The median follow-up was 10.8 years. AR was positive in 39% of the IBC tumors and in approximately one-third of estrogen receptor (ER)-negative and progesterone receptor (PR)-negative tumors. AR positivity was significantly associated with lymphovascular invasion (P = .01) but not with other clinicopathologic parameters. There was a trend toward an association between AR expression and PR expression (P = .07). In univariate survival analysis, patients who had AR-negative/ER-negative tumors had significantly worse overall survival (P = .03) and disease-specific survival (P = .04) than patients who had tumors with other combinations of AR/ER status.

CONCLUSIONS

AR expression was common in IBC tumors, and AR positivity was significantly associated with lymphovascular invasion. Patients who had AR-negative/ER-negative tumors had the worst survival outcomes. Further study with a larger series will be required to delineate the biologic mechanisms of AR and their clinical significance in IBC tumors.