Hormone receptors in breast cancer: more than estrogen receptors

Seventy per cent of breast cancers are luminal carcinomas that express estrogen receptor alpha (ER). For several decades, its expression has been used as a therapeutic target in patients with breast cancer. These therapies are aimed at blocking ER or inhibiting ligand synthesis. The expression of progesterone receptors (PR) is evaluated as a prognostic factor together with ER. It has been shown that there are two predominant PR isoforms with different molecular weight, isoform A and isoform B, which are not distinguished by immunohistochemical techniques. The available evidence indicates that the PR isoform ratio may have both a prognostic and predictive value of the response to antiprogestin treatment. In luminal mammary carcinomas, androgen receptors (AR) are expressed in a high percentage and the AR/ER or AR/PR ratio could be a prognostic factor. In ER negative (-) tumors, AR expression is an indicator of poor prognosis and it is proposed that they may be susceptible to antiandrogen treatment. Finally, the expression of glucocorticoid receptors (GR) would be an indicator of good or bad prognosis in luminal or ER- tumors, respectively. In ER- tumors, metastases express higher levels of nuclear GR than primary tumors and therapies that block GR could improve the efficacy of chemotherapy. Given the crosstalk of pathways triggered by different hormone receptors, it is possible that in the future, a therapeutic scheme can be administered that contemplates the expression of ER, PR isoforms, AR and GR.