SMAD4 and metastasis: SMAD4 expression was related to tumor differentiation (OR = 0.359, 95% CI: 0.238–0.543, P = .000), lymph node metastasis (OR = 0.469, 95% CI: 0.04–0.725, P = .001), tumor node metastasis stage (OR = 0.238, 95% CI: 0.156–0.362, P = .000) and good OS (HR = 0.592, 95% CI: 0.332–0.853, P = .000) in NSCLC.