When used to distinguish NSCLC from normal healthy individuals, the AUCs for serum CEACAM1, CEA and NSE were 0.96 (95% CI: 0.9148 ~ 0.9995; P < 0.001), 0.91 (95% CI: 0.8454 ~ 0.9773; P < 0.001) and 0.98 (95% CI: 0.9302 ~ 1.023; P < 0.001), respectively. The gene discussed is CEACAM5; the disease is non-small cell lung carcinoma.