In terms of diagnostic markers, carcinoembryonic antigen and CA19‐9 has been widely applied in the diagnosis of tumor, but previous studies show that CEA is more suitable for being used in the detection of for tumor recurrence and metastasis; in addition, the CEA levels in intestinal inflammation and adenoma has increased in the tumor, for early colorectal cancer its poor sensitivity and specific degree, CA19‐9 is a good predictor of tumor metastasis.18 The gene discussed is CEACAM5; the disease is colorectal cancer.