A total of 165 non-smokers and 361 smokers were extracted from the TCGA database of lung adenocarcinoma patients; 550 lung adenocarcinoma patients and 550 lung squamous carcinoma patients with EGFR expression; 526 lung adenocarcinoma patients and 550 lung squamous carcinoma patients with EGFR expression. Here, EGFR is linked to lung adenocarcinoma.