Evaluation Of Serum Her2 Extracellular Domain In In Metastatic Gastric Or Gastroesophageal Junction Cancer: Correlation With Her2 Status By Immunohistochemistry And Fluorescence In Situ Hybridization And Clinicopathologic Parameters

4107 Background: To explore the association between serum human epidermal growth factor receptor-2 (HER2) extracellular domain (ECD) and tissue HER2 status, their relationship with clinicopathological parameters and impact on overall survival (OS) in metastatic gastric or gastro-oesophageal junction (GEJ) adenocarcinoma. Methods: A total of 219 histologically confirmed inoperable locally advanced, recurrent, or metastatic gastric or GEJ adenocarcinoma were included. Serum HER2 ECD was measured by chemiluminescent assay. Tissue HER2 status was accessed by fluorescent in situ hybridization (FISH) and immunohistochemistry (IHC) assay. Results: The median serum ECD level was 9.3 ng/ml (range 3.0 to u003e350). Tissue HER2 status was positive (IHC3+ or 2+ with FISH amplification) in 37 patients (16.9%) and negative in 182 patients (83.1%). Statistically significant associations were found between serum HER2 ECD level and HER2 status assessed by IHC and FISH. The ROC-analysis suggested the cutoff of 16.35 ng/ml (24 ...