Investigating and critically appraising the expression and potential role of androgen receptor in breast carcinoma

The potential role of the androgen receptor (AR) as a predictive or prognostic factor in breast cancer remains unclear. We aimed to determine the prognostic significance of AR in a cohort of breast carcinomas with long-term follow-up and to critically appraise this in the context of existing literature. Four hundred and eight cases of invasive breast cancer were incorporated into tissue microarrays (TMAs). All received tamoxifen and comprised 108 cases which relapsed and 300 cases which did not. Mean follow-up time for the former was 84 months (range 1-142, SD 38.8) and for the latter was 77 months (range 11-229, SD 49.7). TMAs were immunohistochemically stained with AR and scored as a continuous variable and using the Allred score. AR expression was significantly associated with grade, recurrence on tamoxifen, non-breast cancer death estrogen receptor alpha (ERα) and progesterone receptor (PR). AR correlated significantly with better overall survival (OS) and disease-free survival (DFS) using an Allred cut-off of 4 (log rank=0.0053 and 0.0044, respectively), and 20% positive tumor cells (log rank=0.0027 and 0.0059, respectively). AR expression was additionally associated with a reduced risk of recurrence following endocrine therapy. In summary, AR positive breast tumors have better OS and DFS and are less likely to recur following endocrine treatment.