While protein overexpression (OE) and/or gene amplification (AMP) in HER2 has been proved to be important in breast and gastric cancer, in lung carcinogenesis, HER2 mutations (MUT) are thought to be more clinically relevant than HER2 OE or AMP [8], although HER2 MUT account for only 1–4%, while HER2 AMP and HER2 OE is reported to account for around 2–20% and 2–35%, respectively [9,10]. This evidence concerns the gene ERBB2 and gastric cancer.