KRAS and adenocarcinoma: Compared with the current, the former were characterized by older age at diagnosis (64.3y vs. 59.9y; P < 0.001), earlier TNM stage (stage I, 47.9% vs. 39.5%; P = 0.017), fewer solid predominance in adenocarcinomas (16.2% vs. 29.5%; P = 0.005), and more EGFR mutation (33.2% vs. 20.7%; P < 0.001) but less KRAS mutation (6.7% vs. 11.9%, P = 0.041).