CEACAM5 and cancer: Carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5/CEA) and CEACAM6 are members of the glycosylphosphatidylinositol-linked immunoglobulin superfamily that are overexpressed in a variety of human cancers11, particularly in gastrointestinal cancer12, 13 and serve as tumor markers for predicting the prognosis of cancer patients14, 15.