Breast 01

Abstract

Background: The role of oestrogen and progesterone receptors in breast cancer has been extensively investigated; however, the androgen receptor has received little attention. We report a flow cytometric method for the measurement of tumour androgen receptor (AR) expression on 43 primary operable breast cancers. AR expression has been correlated with grade, lymph node status, epidermal growth factor receptor (EGFR), and oestrogen receptor alpha (ERα) also measured by flow cytometry. Method: Biotinylated AR antibody AR441 (Dako) was titrated using the LNCaP cell line. Tumour samples were processed through mesh and the resulting suspension were fixed with 2 per cent paraformaldehyde and permeabilized with 0.025 per cent triton prior to incubation with AR antibody, streptavidin PE and 5D3‐FITC. Analysis was performed on cytokeratin‐positive cells by FACScan flow cytometer. Results: Eighty per cent of tumours expressed AR. There was a significant correlation between AR and ERα expression (P‐value = 0.008). No correlation was observed between AR and EGFR expression (P‐value = 0.59). Conclusions: AR appears to be coexpressed with ERα, but not EGFR. The finding of increasing AR expression with increasing grade suggests that AR expression is a more aggressive marker than has hitherto been found by immunohistochemistry. These observations are supported by the previously reported findings of AR expression in 75 per cent of breast cancer metastases, and as the sole steroid receptor in 25 per cent of metastases.