1. normal reference value of carcinoembryonic antigen (CEA): serum <5ug/L. Clinical significance: ① elevated serum CEA is mainly seen in colon cancer, rectal cancer, pancreatic cancer, gastric cancer, liver cancer, lung cancer, breast cancer, etc. Other malignant tumors also have different degrees of positive rate. ②CEA is detected in continuous follow-up. In general, the serum CEA concentration decreases when the disease improves and increases when the disease deteriorates. The percentage of positivity was low, although it was elevated to varying degrees in intestinal diverticulitis, rectal polyps, colitis, cirrhosis, hepatitis and lung disease. ④98% of non-smoking healthy people have serum <5ug/L. About 39% of smokers have CEA >5ug/L. 2. Glycoconjugate antigen 50 (CA50): normal reference value: serum <24U/ml. clinical significance: ①Serum CA50 is elevated in pancreatic cancer, colon cancer, rectal cancer, gastric cancer, etc., especially in patients with pancreatic cancer, which is the most obvious. ②Increased CA50 can also be seen in liver cancer, lung cancer, uterine cancer, ovarian cancer, kidney cancer, breast cancer, etc. (3) CA50 is also elevated in ulcerative colitis, liver cirrhosis, melanoma, lymphoma, and autoimmune diseases. Clinical significance: ① In pancreatic cancer, gallbladder cancer and cholangiocarcinoma, the serum CA19-9 level increases significantly, especially in patients with advanced pancreatic cancer, the serum CA19-9 concentration can reach 400,000 U/ml. -The positive rate is about 7.9%. The positive rate is about 50% for gastric cancer, 60% for colon cancer, and 6.6% for liver cancer. (3) CA19-9 is also elevated to varying degrees in acute pancreatitis, cholecystitis, cholestatic cholangitis, cirrhosis, and hepatitis. These are some of the commonly used indicators, but there are many factors that affect them, and they should be evaluated in the context of other ancillary tests such as ultrasound, CT or MRI, chest X-ray, etc.