As we all know, CEA is a tumor marker for colorectal cancer and other adenocarcinomas, and has recently attracted much attention as a potential marker for ICC: Compared with moderately differentiated ICC, CEA increases are more often seen in poorly differentiated ICC, and the 1-year and 5-year survival of patients with CEA increases are shorter [23, 24]. The gene discussed is CEACAM5; the disease is colorectal cancer.