Studies demonstrate that HER2 protein expression in NSCLC is different from breast cancer: In a study designed to elucidate the concordance between HER2 IHC and in situ hybridization in NSCLC, the results showed that the concordance rate of the HER2 IHC (2+) subgroup was 0.091, which was much lower than 0.975 found in the HER2 IHC (0/1+) subgroup and 0.665 for the HER2 IHC (3+) subgroup [23]. This evidence concerns the gene ERBB2 and breast cancer.