A meta-analysis of 6,135 lung cancer patients indicated that HER2 overexpression determined by IHC is a marker of poor prognosis in NSCLC (HR 1.48; 95% CI: 1.22–1.80), especially in small cell lung cancer, lung adenocarcinoma, and early-stage NSCLC patients (35). This evidence concerns the gene ERBB2 and non-small cell lung carcinoma.