Carcinoembryonic Antigen (CEA) is 0.55ng/mI, which is usually within the normal reference range, if you have any doubt, please go to regular hospital for evaluation. Carcinoembryonic antigen was first found in colon cancer and fetal intestinal tissue, so it is commonly used in the diagnosis of colorectal cancer, and can also be used in the detection of gastric cancer, liver cancer, and breast cancer, and its normal range is usually 2.5ng/mI or less or 5ng/mI or less, and the specific normal reference value is related to the test reagent. Carcinoembryonic antigen can also be used to determine the prognosis of cancer patients. If the serum carcinoembryonic antigen decreases after treatment, the disease is in remission and the prognosis is good; if the disease progresses, the serum carcinoembryonic antigen increases and the prognosis is poor. But smoking, pregnancy and cardiovascular disease, diabetes mellitus, non-specific colitis and other diseases, 15% to 53% of patients with serum CEA will also be elevated, so CEA is not a specific marker of malignant tumors, in the diagnosis of only auxiliary value. Elevated carcinoembryonic antigen does not necessarily mean that it is cancer, but it may also be caused by physiological reasons, which need to be further examined to clarify the diagnosis and timely treatment. If there is any abnormality, suspicion or diagnosis of tumor, it is recommended to go to regular hospitals for comprehensive assessment of the condition and follow the doctor’s instructions for treatment to avoid delaying the condition.