HER2 gene amplification in esophageal squamous cell carcinoma is less than in gastroesophageal junction and gastric adenocarcinoma

The aim of the present study was to detect the amplification of the human epidermal growth factor receptor 2 (HER2) gene in esophageal squamous cell carcinoma (ESCC), gastroesophageal junction adenocarcinoma (GEJAC) and gastric cancer (GC), as well as to understand the pathological meaning of HER2 gene amplification with regard to clinico-pathological parameters in these types of cancer. HER2 gene amplification was evaluated by fluorescence in situ hybridization (FISH) in surgically obtained specimens from 76 cases of ESCC, 50 of GEJAC and 48 of GC, as well as 21 specimens of tumor-adjacent normal epithelium as a control group. The HER2 gene amplification rates in ESCC, GEJAC and GC were 3.9 (3/76), 24.0 (12/50) and 18.8% (9/48), respectively. The rates of HER2 gene amplification in GEJAC and GC were significantly higher compared with ESCC (χ(2)=11.563, P<0.001 and χ(2)=7.375, P<0.007, respectively). HER2 gene amplification was not detected in the normal esophageal or gastric mucosa samples. In ESCC, HER2 gene amplification was correlated with the invasion of the ESCC cells, vascular invasion and lymph node metastasis (χ(2)=4.789, 3.858 and 5.354, respectively; all P<0.05). However, in GEJAC and GC, no correlations were observed between HER2 amplification and the gender, age, degree of differentiation, invasion, vascular invasion and lymph node metastases of the patients (all P>0.05). The rate of HER-2 gene amplification was low in ESCC, although the amplification of HER-2 was correlated with tumor metastasis in these patients. The rates of HER-2 gene amplification in GEJAC and GC were higher compared with ESCC. Therefore, compared with ESCC, GEJAC may be more similar to GC with regard to HER-2 gene amplification features.