Discordant ER, PR, and HER2 status between primary and metastatic breast cancer as prognostic factor.

1039 Background: The receptor status including estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) of metastases may be different from that of the primary breast cancer. This discordance of receptor status may influence patient prognosis. We investigated discordance of receptor status between primary breast cancer and distant metastases in the same patients and its effect on prognosis. Methods: ER, PR, and HER2 status in metastases were available in 173 patients. The receptor status was compared between primary tumors and metastases. Tumors were classified as triple-negative breast cancer (TNBC) or non-triple-negative breast cancer (non-TNBC) according to receptor status and as concordant and discordant depending on the difference of receptor status between primary and metastatic breast cancer. Survival analysis was performed depending on concordant or discordant receptor status. Results: Discordance for ER, PR, and HER2 was 18.5%, 23.7%, and 10.4%, resp...