Steroid hormone receptor expression in male breast cancer

Aims: To investigate expression of the steroid hormone receptors estrogen receptor (ER)-alpha and -beta, progesterone receptor (PR) and androgen receptor (AR) in male breast cancer. Methods: Specimens from 16 male breast cancers were immunostained for ER alpha, ER beta, PR and AR. Findings: Eighty-seven percent of tumours expressed ER alpha, 93% PR, 87% ER beta and 87% AR. Staining for ER alpha and PR was confined exclusively to the nuclei of epithelial cells with some heterogeneity. Nuclear immunoreactivity was also observed with AR. Again this was restricted to epithelial cells but tended to be more uniform. ER beta was seen in the nuclei of epithelial cells and also in stromal fibroblasts and lymphocytes. Analysis of serial sections revealed a similar pattern of staining with ER beta and AR in epithelial cells. Conclusions: In addition to expression of the better known steroid receptors, ER alpha, PR and AR, we have demonstrated a high rate of expression of ER beta in male breast cancer. This is in keeping with the generally high steroid receptor expression seen in males. However, the abundance of ER beta expressed in this small series of male breast cancer is in contrast to female breast cancer where ER beta expression is often reduced. (c) 2005 Elsevier Ltd. All rights reserved.