Androgen receptor expression in circulating tumor cells of metastatic breast cancer patients.

Abstract

1087Background: The androgen receptor (AR) is of clinical relevance in metastatic breast cancer (mBC): AR has been associated with resistance to endocrine therapy and could be a potential target for therapy, especially in the triple negative (TN) subtype. A minimal-invasive way to determine AR expression is by characterization of circulating tumor cells (CTCs). We therefore assessed AR mRNA expression in CTCs (CTC-AR) from mBC patients representing different breast cancer subtypes in relation to outcome on endocrine therapy and 25 genes related to the ER and AR pathways. Furthermore, we assessed AR in matched primary tumors and CTC samples taken at advanced disease. Methods: AR and AR- and ER-related gene expression levels were measured in CellSearch-enriched CTCs from 133 mBC patients with ≥5 CTCs and in 48 matched formalin-fixed paraffin embedded primary tissues using quantitative reverse-transcriptase PCR. AR was considered positive if the expression was 1 standard deviation higher than the expression ...