IHC based on membranous staining according to breast guidelines [74]:>0: HER2 negative;>1+: needs to be confirmed by further studies whether 1+ should be considered negative or as having a HER2 low expression;>2+, 3+: HER2 positive.Due to the poor concordance between FISH and IHC in NSCLC, FISH confirmation is not required for NSCLC patients with IHC 2+/3+ to define positive HER2 expression. This evidence concerns the gene ERBB2 and non-small cell lung carcinoma.