Androgen receptor expression in triple negative breast carcinoma and its association with the clinicopathological parameters

INTRODUCTION: Androgen receptor (AR) is the most frequently expressed biomarker in all subtypes of breast carcinoma. Triple negative breast carcinoma (TNBC) is breast carcinoma that lacks oestrogen and progesterone receptors immunoexpression as well as absence of HER2/neu gene amplification. This makes targeted therapy not feasible in this cancer and hence has poorer prognosis. Detecting AR expression could be another milestone in the management of TNBC, as AR is a prognostic, predictive marker and potential index for targeted treatment. This study aimed to assess expression of AR in TNBC by immunohistochemistry and its association with clinicopathological parameters.

METHODS: We analysed the expression of AR in 97 TNBC cases from Penang General Hospital for a period of 3 years (2014 to 2017). Androgen receptor immunoreactivity was considered positive if ≥ 1% of tumour cells nuclei were stained irrespective of staining intensity.

RESULTS: The prevalence of AR expression in TNBC was 31% (30/97), with the proportion of AR-positive tumour cells ranged from 1% to 90%. These include 23 invasive carcinomas, no special type (NST) and 7 other invasive carcinoma subtypes (papillary, lobular, clear cell and medullary carcinomas). Sixty-seven cases (69%) that showed AR immunonegativity were invasive carcinomas, NST (n=60), clear cell carcinoma (n=1) and metaplastic carcinoma (n=6). Androgen receptor immunoexpression was inversely correlated with tumour grade (p=0.016), but not the tumour stage, tumour size and nodal status.

CONCLUSION: AR is expressed in about one-third of TNBC and loss of AR immunoexpression does not predict adverse clinical outcomes. Larger cohorts for better characterisation of the role of AR immunoexpression in TNBC are warranted.