Correlation of Expression of Breast Biomarkers in Primary and Metastatic Breast Carcinomas: A Single-Institution Experience.

OBJECTIVE: Changes in the status of estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) in metastatic breast carcinomas are frequently reported. We examined the change in the status of biomarkers in metastatic breast carcinomas.

STUDY DESIGN: This study cohort was composed of 137 metastatic breast carcinomas (58 surgical and 79 cytological specimens) with existing primary tumors during a study period from 2013 to 2015.

RESULTS: The overall change rates in metastases were 9, 21 and 6% for ER, PR and HER2, respectively. All changes were from positive in the primary tumor to negative in the metastases. The ER change rate was significantly higher in the cytological than in the surgical metastases. Six of 14 cytological metastases with positive HER2 in primary tumors showed a change in HER2 status, including 5 fluid specimens and 1 fine-needle aspiration (FNA); the other 8 had no change in HER2 status, and included 7 FNAs and 1 fluid specimen.

CONCLUSION: The significant percentage of cases with a change in biomarker status supports the recommendation by the College of American Pathologists to test breast biomarkers in metastases. HER2 status change was mostly identified in fluid specimens; however, the small sample size in our cohort and the fact that HER2 fluorescence in situ hybridization was not performed may warrant further studies.