Clinicopathologic significance of androgen receptor expression and discordant receptor status during progression in breast cancer

The role of androgen receptor (AR) as a prognostic marker has been proposed in breast cancer. This study investigated AR status and its clinical significance in breast cancer, especially in triple negative breast cancer (TNBC). We also evaluated discordant AR status during the process of lymph node metastasis, locoregional recurrences (LRR) and distant metastasis. From January 2005 to December 2010, we retrospectively reviewed 120 patients including 55 TNBC patients diagnosed as invasive carcinoma with no special type (NST), who were treated at the Kangbuk Samsung Hospital. Tissue microarray was constructed and immunohistochemical expression of AR was performed for 120 invasive carcinomas, NST specimens and matching samples from 28 lymph node metastasis, 2 LRR and 8 distant metastases. AR expression was found in 35.0% (42/120) of the total patients and 14.5% (8/55) of those diagnosed as TNBC. Positive expression of AR was significantly correlated with smaller tumor size, early T stage, fewer lymph node metastases, early AJCC stage, lower histologic grade, estrogen receptor/progesterone receptor positivity, more luminal A type, less TNBC, longer disease-free survival and overall survival, fewer distant metastasis and no deaths from breast cancer (all P < 0.05). AR was a favorable prognostic marker for disease free survival in univariate analysis (P = 0.041). The discordance rate of AR status between primary and recurrent/ metastatic disease was 21.6%. AR expression was associated with favorable clinicopathological outcomes in the whole study population. AR status can be altered during tumor progression.