Prognostic Value of Estrogen Receptor α and Progesterone Receptor Conversion in Distant Breast Cancer Metastases

BACKGROUND: Changes in the receptor profile of primary breast cancers to their metastases (receptor conversion) have been described for the estrogen receptor alpha (ER alpha) and progesterone receptor (PR). The purpose of this study was to evaluate the impact of receptor conversion for ER alpha and PR on survival in a large group of distant non-bone breast cancer metastases. METHODS: Receptor conversion was studied by immunohistochemistry in a group of 233 metastatic breast cancer patients. Kaplan-Meier overall survival curves were plotted, and differences between the curves were analyzed by log-rank analysis. The additional prognostic value of conversion to established prognosticators was studied by Cox regression. RESULTS: Overall survival of patients showing conversion from positive to negative ER alpha or PR, or from negative to positive ER alpha or PR, or remaining receptor negative was comparable, and significantly worse than patients remaining receptor positive. ER alpha or PR receptor conversion from positive in the primary breast tumor to negative in distant metastases has independent negative prognostic value. CONCLUSIONS: ER alpha or PR receptor conversion from positive in the primary breast cancer to negative in distant metastases has negative prognostic value. Cancer 2012;118:4929-35. (C) 2012 American Cancer Society.