Anh Thu Phan et al. reported a high level of concordance between ISH and IHC analyses, an amplification rate of the HER2 gene of 15.9% and protein overexpression of the HER2 gene of 24.5%, and elevated HER2 heterogeneity in gastric cancers (68.8% phenotypic heterogeneity and 57.6% genotypic heterogeneity).38 This evidence concerns the gene ERBB2 and gastric cancer.