Serum tumor markers demonstrated normal alpha-fetoprotein (AFP) and carcinoembryonic antigen (CEA) levels, but a markedly elevated carbohydrate antigen (CA)19–9 level of 5949.5 U/mL (0–36 U/mL), which can be elevated in pancreatic, gastric, hepatobiliary, and colonic malignancies. This evidence concerns the gene CEACAM5 and digestive system cancer.