Traditionally, several preclinical and clinical studies focusing on EGFR-positive (including EGFR mutant, high gene copy number and overexpression) NSCLC patients suggested that increased copy number of ErbB2 gene was susceptible to gefitinib therapy and was correlated with better response rate, disease control rate, and survival preclinical studies reported that gefitinib has a prominent antiproliferative effect on tumors with ErbB2 overexpression [41–43]. This evidence concerns the gene ERBB2 and non-small cell lung carcinoma.