Comparative Study of Receptor Expression Diversity Between Primary and Recurrent Lesions in Patients with Metastatic Breast Cancer.

e12062Background: Tumor phenotype may alter during the progression of breast cancer (BC). Our aim in this study is to compare the discordance in estrogen receptor (ER) / progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) between primary and recurrent / metastatic lesions (RML) and also to evaluate the prognostic significance of change in tumor phenotype on survival of patients with metastatic BC. Methods: Medical records of 6638 patients with BC from two large center followed between January 1992 and August 2015 were retrospectively analyzed. Of these population, 393 patients whose recurrence or progression were histologically proven by biopsy or surgical resection were enrolled into this study. Results: Fifty-three of patients (13.5%) had metastatic disease at presentation. Recurrent biopsy was performed from distant metastasis sites in 252 (64.1%) patients or from locoregional soft tissues / lymph-nodes in 141 (35.9%) patients. At a median follow up time of 74.8 months (range...