In lung cancer patients, DPP4 inhibitor only group (n = 419) showed HR of 0.93 (95% CI: 0.83‐1.03, P = 0.153) while the group with combined use of DPP4 inhibitors and metformin (n = 559) showed HR of 0.88 (95% CI: 0.80‐0.97, P = 0.010). This evidence concerns the gene DPP4 and lung cancer.