Our results showed that SMAD4 expression was associated with 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), and tumor node metastasis (TNM) stage (OR = 0.238, 95% CI: 0.156–0.362, P = .000) in NSCLC patients. The gene discussed is SMAD4; the disease is non-small cell lung carcinoma.