Breast cancer patients co-expressing estrogen receptor alpha and/or progesterone receptors and HER2/neu: Response to adjuvant therap

699 Background: In breast cancer patients ERα/PR (HR) predict the response to endocrine therapy (mainly tamoxifen: Tx), and HER2/neu predicts the response to trastuzumab. These molecules are inversely correlated (not all reports agree on this), however, in a few cases they are co-expressed. Some but not all studies suggest that HR+/HER2/neu+ patients have poor response to Tx making this special group a matter of debate. In this prospective study we report the response to adjuvant therapy in a relatively small subgroup of patients co-expressing HR and HER2/neu. Methods: We have analysed the data from our patients: n=516, follow-up: 5–10 years, consecutive stage I-II cases, tumor biopsies studied by immunohistochemistry to integrate the molecular markers ERα, PR, PCNA, HER2/neu, p53 and P170 with the clinicopathological data to obtain prognostic information (J Steroid Biochem Mol Biol 67:431–437, 1998). ERα/PR+: nuclear receptors in ≥ 10% of cancer cells, HER2/neu+: membrane staining in >1% of cancer cells ...