Aim: We investigated whether serum concentrations of the HER2 extracellular domain (ECD) can be used as an alternative to test tissue HER2 status in metastatic gastric cancer.
Materials & methods: A total of 133 cases of metastatic gastric cancer were included in present study. Serum HER2 ECD was measured by chemiluminescence immunoassay (CLIA). Receiver operating characteristic curve analysis was used to determine optimal serum HER2 ECD concentrations for differentiation between positive and negative HER2 status.
Results: The median level of serum HER2 ECD was 9.6 ng/ml in metastatic gastric cancer patients. There was a significant relationship between serum and tissue levels of HER2 protein (p < 0.001). Area under the curve for serum HER2 ECD was 0.771 (95% CI: 0.682-0.860).
Conclusion: Levels of serum HER2 ECD are highly correlated with tissue HER2 status in metastatic gastric cancer. Serum HER2 ECD assay can be considered as a potential alternative for tissue HER2 status.
Keywords: ECD; HER2; extracellular domain; metastatic gastric cancer; serum.