Discordances in Estrogen Receptor Status, Progesterone Receptor Status, and HER2 Status Between Primary Breast Cancer and Metastasis

Abstract

This study confirms that discordance in ER and PR receptor expression between the primary breast tumor and the corresponding metastatic lesions is high, whereas HER2 status remains relatively constant. Chemotherapy, and specifically anthracycline-based chemotherapy, was associated with switch in ER status. These results were obtained in a selected population of patients; further studies are warranted to confirm these data and to determine the interest of systematic rebiopsy in the metastatic setting.