302 - Study on Serum HER2 Extracellular Domain Expression in Early Stage Breast Cancer Patients

Abstract

ABSTRACT Background The measurement of the human epidermal growth factor receptor 2 (HER2) protein in the serum of metastatic breast cancer patients has now been reported, but there are no consistent data to support the clinical utility of serum HER2 extracellular domain (ECD) for patients with early breast cancer. We aimed to evaluate the correlation between serum HER2 ECD levels and tumor HER2 status, and analyze their relationship with clinicopathological parameters in patients with early stage disease. Methods A prospective study was conducted on 232 breast cancer patients with stage I-II diseases before treatment. Preoperative serum samples were measured by enzyme-linked immunosorbent assay (ELISA). Tissue HER2 status was analyzed by immunohistochemistry and fluorescence in situ hybridization assays. Results The median serum HER2 ECD concentration was 6.8 ng/ml (range 1.3 - 42.1 ng/ml). The best diagnostic cut-off value was 7.4 ng/ml (with 72.9% sensitivity and 85.3% specificity), which was lower than HER2 ECD cut-off value with metastasis breast cancer (15 ng/ml). High serum HER2 ECD levels were reported in 89 patients (38.3%) and HER2 tissue positive expression was observed in 77 patients (33.2%) with a moderate concordance of 76.7%. Elevated serum HER2 ECD correlated with postmenopausal (p Conclusion HER2 ECD, which is associated with poor prognosis, may provide more additional information compared with HER2 tissue alone. We support that it is necessary to decrease the cut-off value in evaluating serum HER2 ECD level for early stage breast cancer. Disclosure All authors have declared no conflicts of interest.