In addition, the KRAS mutation rate was higher in smokers (14/60, 23.3%) than in never smokers (7/57, 12.3%; P = 0.15), in patients with squamous (3/15, 20%) than in those with adenocarcinoma (18/96, 18.8%; P = 1), and in patients with early-stage (2/8, 25%) than in those in late-stage (19/109, 17.4%; P = 0.63). Here, KRAS is linked to adenocarcinoma.