Comparative study of receptor discordance between primary and corresponding metastatic lesions in breast cancer

It is well-known that tumor phenotype may change during the progression of breast cancer (BC). The purpose in this study was to compare the discordance in estrogen receptor (ER), progesterone receptor (PgR) 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 in patients with metastatic BC. The medical records of 6638 patients with BC from two breast centers treated between 1992 and 2015 were retrospectively analyzed. Of the 6638 patients, 549 cases in whom recurrence was histologically proven by biopsy or by surgical resection were enrolled into this study. Our presentation 13.5% of the patients had metastatic disease. Biopsy on recurrence was obtained from distant metastasis sites in 250 (63.6%) patients or from locoregional soft tissues/lymph-nodes in 143 (36.4%). Receptor discordance in ER, PgR and HER2 expressions between primary and RML were 27.2% (p=0.32), 38.6% (p