When the cut-off value of CEA was 4.7 ng/ml, the fluctuation range of CEA was 2.35 ± 2.0 ng/ml in the control group and was 3.5 ± 3.03 ng/ml in the pretreatment group, which were significantly lower than in the esophageal cancer group (P < 0.05). The gene discussed is CEACAM5; the disease is esophageal cancer.