The diagnostic performance of each marker in specific gastrointestinal tumors is summarized as follows: In GC patients, GBC and CRC, CEA had better diagnostic efficacy (AUC = 0.750, AUC = 0.735, AUC = 0.709), while CA199, CA125 and CA724 had poor diagnostic efficacy (Figs. 2B, E, F, and 3B, E, F) . The gene discussed is CEACAM5; the disease is gastric cancer.