Carcinoembryonic antigen greater than 1000ng/mL suggests abnormal elevation of carcinoembryonic antigen,. Carcinoembryonic antigen (CEA) is a tumor marker commonly used in clinical practice, with a normal reference value of “<5ng/mL”.Mild elevation of CEA can be seen in non-neoplastic diseases such as pancreatitis, biliary obstruction, colon polyps, ulcerative colitis, and so on. However, when CEA is greater than 1000 ng/mL, it suggests that the patient has a higher risk of having a neoplastic disease such as colorectal cancer, gastric cancer, hepatocellular carcinoma, pancreatic cancer, medullary thyroid cancer, choriocarcinoma, and other neoplastic diseases. If carcinoembryonic antigen is found to be greater than 1000ng/mL, patients should go to regular hospitals in time, follow the diagnosis and treatment advice of specialists, improve relevant auxiliary examinations, and formulate comprehensive diagnosis and treatment plan by combining with clinical manifestations of the patients, as well as standardize treatment and follow up.