The actual predictive value of oestrogen receptor (ER) β 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 ERα and progesterone receptor (PR). The main purpose of this study was to compare ERβ expression levels before and after neoadjuvant chemotherapy or endocrine therapy and to explore a possible predictive value of ERβ. 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 ERα, PR, total ERβ (ERβt), ERβ1, ERβ2 and the proliferation-related antigen Ki-67 using immunohistochemistry. A marked expression of ERβt significantly correlates with low proliferation rates after PST (p=0.0013) and with response to it. Further most tumours decreased ERβ1 expression with PST. A marked ERβ2 expression was observed predominantly in responders and significantly decreased during chemotherapy (p=0.047). Results on ERα and PR corroborate findings of previous studies. Our data demonstrate that changes of ERβ expression occur during PST and that total ERβ expression and ERβ2 may have a predictive value for PST.

Related Articles