The Role of Previous Therapies and Sites of Metastasis as Influencing Factors on Discordance of ER, PR and HER2 Status Between Primary and Metastasized Breast Cancer

Background/Aim: The aim of the present study was to analyze metastasized breast cancer (BC) patients with regard to the discordance of estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2). We especially aimed to analyze the association between the change of tumor biology and previous treatment or metastatic sites. Patients and Methods: Patients with metastasized BC who were treated at the Department of Gynecology/Breast Center of the University Hospital of Cologne were analyzed. Results: Loss of HER2 occurred more frequently in lymph node metastases that were not in the axillary region (p=0.026). Letrozole showed a significant correlation with loss of ER and/or PR (p=0.041). Improved overall survival and post-metastasis survival were noticed with a gain of HER2 (p=0.044 and p=0.009, respectively) and concordant positive ER and PR status (p=0.002 and p=0.001, respectively). Conclusion: The discordance of receptors and the dependence of BC on therapies as well as metastatic sites stresses the necessity of early sample taking to offer patients suitable therapy options.