Evaluation of ERα, PR and ERβ isoforms in neoadjuvant treated breast cancer

Abstract

Abstract. The actual predictive value of oestrogen receptor (ER) ß for treatment decisions in breast cancer is still unclear. Retrospective studies using preoperative systemic therapy (PST) revealed that chemotherapy but also endocrine therapy can lead to alterations in expression levels of ER· and progesterone receptor (PR). The main purpose of this study was to compare ERß expression levels before and after neoadjuvant chemotherapy or endocrine therapy and to explore a possible predictive value of ERß. Matching 'baseline' biopsies and post-therapy surgical specimens of 69 breast cancer patients treated with neoadjuvant anthracycline-or taxane-based chemotherapy or with aromatase inhibitors were analyzed for expression levels of ER·, PR, total ERß (ERßt), ERß1, ERß2 and the proliferation-related antigen Ki-67 using immunohistochemistry. A marked expression of ERßt significantly correlates with low proliferation rates after PST (p=0.0013) and with response to it. Further most tumours decreased ERß1 expression with PST. A marked ERß2 expression was observed predominantly in responders and significantly decreased during chemotherapy (p=0.047). Results on ER· and PR corroborate findings of previous studies. Our data demonstrate that changes of ERß expression occur during PST and that total ERß expression and ERß2 may have a predictive value for PST.