Steroid hormone receptor expression in male breast cancer

Aims To investigate expression of the steroid hormone receptors estrogen receptor (ER)-α and -β, progesterone receptor (PR) and androgen receptor (AR) in male breast cancer. Methods Specimens from 16 male breast cancers were immunostained for ERα, ERβ, PR and AR. Findings Eighty-seven percent of tumours expressed ERα, 93% PR, 87% ERβ and 87% AR. Staining for ERα 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. ERβ 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 ERβ and AR in epithelial cells. Conclusions In addition to expression of the better known steroid receptors, ERα, PR and AR, we have demonstrated a high rate of expression of ERβ in male breast cancer. This is in keeping with the generally high steroid receptor expression seen in males. However, the abundance of ERβ expressed in this small series of male breast cancer is in contrast to female breast cancer where ERβ expression is often reduced.