None of the patients had abnormal levels of gastrointestinal tumor markers [carbohydrate antigen (CA)199, CEA and CA724], and an increased 5-Serotonin (5-HT) content in the serum and an elevated 5-hydroxyindoleacetic acid (5-HIAA) level in the urine were not detected prior to the pathological diagnosis. The gene discussed is CEACAM5; the disease is digestive system neoplasm.