Normal value of carcinoembryonic antigen <5.0μg/L, if found 500μg/L, it means higher chance of having cancer. Carcinoembryonic antigen is a very important tumor marker. Elevated carcinoembryonic antigen can be seen in malignant tumors, such as gastric cancer, colon cancer, liver cancer, pancreatic cancer, breast cancer, ovarian cancer and so on. It can also be seen in benign diseases, such as hepatitis, cirrhosis, intestinal inflammation, diabetes, and smokers. If carcinoembryonic antigen reaches 500μg/L, it is very likely to be caused by the organism suffering from cancer, and further examination is recommended to avoid delaying the condition. If cancer is detected, one should actively cooperate with doctors for treatment, such as surgical treatment, chemotherapy, radiotherapy and targeted therapy, to improve the prognosis.