Taking the entire study cohorts of CRC and lung cancers together, patients using DPP4 inhibitors only (n = 775) had hazard ratio (HR) of 0.89 (95% CI: 0.82‐0.97, P = 0.007) while the patients with combined use of DPP4 inhibitors and metformin (n = 1011) showed HR 0.83 (95% CI: 0.77‐0.90, P < 0.0001). This evidence concerns the gene DPP4 and lung cancer.