Immunohistochemical demonstration of androgen receptor in breast cancer and its relationship to other prognostic factors.

Androgen actions and androgen receptors (ARs) have been described in human breast cancer cells both in vivo and in vitro. With the use of a new monoclonal anti-AR antibody, AR was immunohistochemically demonstrated in 76 primary breast cancers. Positive immunostaining was found in 79 percent of tumours. Benign ductal epithelium was often AR-positive whereas the tumour stroma lacked AR immunoreactivity. At the subcellular level, nuclear localization was evident using either cross-linking (Zamboni's fluid) or precipitating (acetone) fixatives on frozen sections. The use of archival paraffin-embedded tissue yielded negative results. A significant association was found between expression of AR and oestrogen receptor (ER) (P = 0.0006) determined immunohistochemically on adjacent sections. Most progesterone receptor (PR)-negative cases were also AR-negative (P = 0.02), but significant proportion (38 percent) of AR-positive tumours did not contain PR. Unlike ER, AR was not associated with aneuploidy or erb-B2 oncogene overexpression, and was only marginally associated with tumour proliferation rate (S-phase fraction by DNA flow cytometry). In conclusion, the close association of AR with ER and PR suggests that immunohistochemical determination of androgen receptors may have value as a prognostic factor and/or predictor of response to endocrine therapy.