The diagnostic efficacy of any combination for CEA, CA199 and CA125 in the tumor group for GC, EC, PC, GBC and CRC patients was higher than that of a single marker, and the combination of CEA + CA199 + CA125 had the best diagnostic efficacy (tumor: AUC = 0.780, GC: AUC = 0.776, EC: AUC = 0.650, PC: AUC = 0.896, GBC: AUC = 0.840, CRC: AUC = 0.793) (Fig. 5A–F). The gene discussed is CEACAM5; the disease is colorectal carcinoma.