CA199 is a glycoantigen 199, one of the tumor markers, with a normal range of <37 U/ml, and is clinically significant when it exceeds the normal index. CA199 is at risk of cancer when it is abnormally elevated and should be promptly examined by a doctor for related aspects or promptly reviewed for early detection, diagnosis and treatment. mildly elevated CA199 is commonly associated with benign diseases such as inflammation, mostly in hepatitis, pancreatitis, gastritis, cholecystitis, and bile duct stones. If CA199 is significantly elevated, more than two times the normal value, or even increasing by more than ten or tens of times, or if it continues to increase, the possibility of cancer should be considered. CA199 is more sensitive to liver, pancreatic, stomach, gallbladder and colon cancers, and is useful for diagnosing these cancers. In addition, abnormal increases in CA199 can be seen in cervical cancer, lymphoma and ovarian cancer. However, the CA199 value alone cannot be used to determine whether the cancer is present or not. Other relevant tests such as CT, MRI, ultrasound, gastroscopy, etc. of the liver, gallbladder, pancreas or other parts of the body, or biopsy of relevant pathology should be performed to make a specific judgment. If cancer is diagnosed, surgery should be performed in time to remove the cancer, together with radiotherapy and chemotherapy to avoid aggravation of the disease.