Androgen receptors in operable breast cancer: relation to other steroid hormone receptors, correlations to prognostic factors and predictive value for effect of adjuvant tamoxifen treatment

Abstract

Steroid hormone receptors have been evaluated as independent prognostic factors as well as predictive factors for endocrine manipulation in the clinical management of breast cancer. The contribution of each receptor or combinations of different receptors remains controversial. In cytosols from 224 patients with operable breast cancer (stages I & II), estrogen receptor (ER), progesterone receptor (PgR) and androgen receptor (AR) content have been measured. An improved AR-assay has been used in order to circumvent some of the problems inherent in other methods. In this study, 91.1% of the patients were classified as AR 'positive' (i.e. greater than or equal to 10 pmol/g). The steroid hormone receptors were significantly correlated (P less than 0.001). Taking the median value of AR as cut-off (50.5 pmol/g), a significantly higher incidence (P = 0.004) of node negative patients was found in the group with a lower AR content. In a multivariate analysis the AR category (median value used as cut-off) was shown to be an independent predictor of the likelihood of axillary metastases (P = 0.001). AR category, however, did not reveal any significant prognostic information concerning relapse free survival. A subpopulation of node positive patients with ER positive tumors, have been included in a randomized trial on the role of tamoxifen as an adjuvant treatment compared with no endocrine treatment. In a multivariate analysis, PgR status was shown to be a single independent prognostic factor (P = 0.016) for relapse free survival in patients with a lower AR content (less than median value). The improved AR assay used in the present study may provide a basis for more correct estimation of the AR content in an individual tumor. The present study suggests that AR analysis and the use of a well-chosen cut-off level may add information about tumor biology to increase our understanding of breast cancer biology and treatment.