CEACAM5 and neoplasm: Tumor markers including serum pancreatic enzymes and carbohydrate antigens, such as carbohydrate antigen 19-9 (CA19-9), carcinoembryonic antigen (CEA), s-pancreas-1 antigen (SPan-1), and duke pancreatic monoclonal antigen type 2 (DUPAN-2), have been used for complementary diagnosis [5,6,7].