Comparison of Estrogen receptor, Progesterone receptor and HER2 status between primary breast cancer and synchronous axillary lymph node metastasis in Thammasat University Hospital

Introduction: Assessment of estrogen receptor (ER), progesterone receptor (PR) and HER2 status is routinely carried out on primary breast tumor in order to select appropriate adjuvant therapy. Many studies have shown changes in expression of ER, PR and HER2 between primary tumor and metastatic sites and some studies have also demonstrated a discordance of expression between primary breast tumor and synchronous axillary metastases. Objectives: To determine discordance rate of ER, PR and HER2 status in primary breast tumor and synchronous axillary lymph nodes of individual patients. Methods: Descriptive study of all breast cancer patients who have axillary lymph node metastasis and underwent surgery from January 2011 to December 2015 were included in this study. Weexcluded the patients who received neoadjuvant therapy or recurrent disease. Then paraffin blocks of patients were collected for additional staining of ER, PR and HER2 in axillary lymph node. The results were recorded and analyzed. Results: ER positivity was observed in 74.7% of the primary tumors which were reduced to 71.7% in synchronous axillary lymph node metastasis. PR were positive in 71% of the primary tumors as compared to 71% in synchronous axillary lymph node metastasis. HER2 status expression was noted in 26% and 24% of the primary tumor and synchronous axillary lymph node metastasis respectively. In case to case comparison ER, PR and HER2 status showed 11.1%, 20.2 % and 10.1% discordance in primary and synchronous axillary lymph node metastasis respectively. Conclusion: ER, PR and HER2 biomarkers showed significant concordance between primary and synchronous axillary lymph node metastasis among Thai patients at Thammasat University.