ERBB2 and esophageal squamous cell carcinoma: Thus, Rong et al., in a retrospective analysis of 857 consecutive ESCC patients, showed that with immunohistochemistry only 1.5% of cases displayed strong HER2 positivity (3+) and 6.1% showed equivocal HER2 positivity (2+): dual-color in situ hybridization showed that 100% of patients with HER2 (3+) exhibited HER2 gene amplification, whereas only 18.5% of those with HER2 (2+) had HER2 gene amplification [73].