ERBB2 and esophageal squamous cell carcinoma: Wu et al reported that the rate of HER2 over-expression was 14.1% according to immunohistochemistry (IHC) in ESCC (19), while HER2 positivity was demonstrated in 17% of resected esophageal adenocarcinomas in a study by Yoon et al (20) and HER2 protein overexpression was 10.4% in ESCC according to the study by Zhan et al (21).