Receptor discordance rate and its effects on survival in primary and recurrent breast cancer patients.

PURPOSE: The receptor status of breast cancer plays a critical role in clinical practice. During the metastatic process, a change in the biological characteristics of the tumor can be seen. This study aimed to investigate the hormone receptor and HER2 status changes between primary and recurrent breast cancers and their effect on survival. METHODS: Eighty-six breast cancer patients with biopsy- proven local recurrences or distant metastases during the follow-up period were included in the study. Patients with metastatic disease at the time of first diagnosis or with history of previous neoadjuvant chemotherapy were excluded. RESULTS: Forty-three of the 86 patients (50%) had changes in at least one of the estrogen receptor (ER), progesterone receptor (PR), or HER2. ER, PR and HER2 discordance rates were 12.7, 38.3, and 15.1%, respectively, and PR discordance was significantly higher (p=0.000). Among all molecular subtypes, the triple negative breast cancer (TNBC) subtype showed the least change. When the effect of chemotherapy on receptor change was analyzed, PR discordance was significantly higher in the group who received chemotherapy (p=0.029). Analysis of the hormonotherapy effects on receptor discordance revealed results similar to those of chemotherapy. Only the PR discordance was significantly greater in the group that received hormonotherapy (p=0.000). None of the three receptor discordances or loss of any receptor were related to survival. Primary tumor TNBC subtype and disease-free-interval (DFI) shorter than 5 years were found as independent prognostic factors that negatively affected overall survival (OS). CONCLUSION: This study showed that during recurrent disease there was 50% discordance in the expression of ER, PR, and HER2. The receptor showing the greatest discordance and influence from the systemic treatment was PR. A significant relationship between receptor discordance and survival could not be demonstrated in our study.