Comparison between HER2 extracellular domain in serum and HER2 overexpression in breast cancer tissue

e11066 Background: Immunohistochemistry (IHC), fluorescent in situ hybridization (FISH) and chromogenic in situ hybridization (CISH) are reliable ways to identify human epidermal growth factor receptor 2 (HER2) and HER2 amplification. Each technique requires access to tumor tissue and high-quality tissue sample, which may not be available in some patients. HER2 extracellular domain (ECD) may be shed to the serum. The importance of serum ECD in breast cancer (BC) is not yet determined. The first aim of this study was to explore the correlation between serum ECD and HER2 expression in breast cancer tissue. The second aim was to compare ECD levels with clinical and pathological features in early BC patients. Methods: This prospective trial included patients with stage I–III BC. Serum HER2 ECD levels were measured by ADVIA Centaur automated assays before surgical resection of the tumor. Tissue HER2 status was detected by IHC in all tumors. CISH test was utilized in HER2: +2 tumors by IHC. Serum ECD >15ng/ml w...