How much increase in CEA is considered indicative of cancer?

CEA refers to carcinoembryonic antigen, which is a type of tumor marker. Generally, elevated levels of carcinoembryonic antigen can be observed in various types of tumors and it is commonly used as an aid in the diagnosis of malignant tumors and monitoring for recurrence. A CEA level exceeding 5.0 ng/mL should raise suspicion for the presence of a tumor. The details are as follows:

Carcinoembryonic antigen is an acidic glycoprotein with characteristics similar to embryonic antigens. It can exist as a structural membrane protein on the surface of cancer cells and is a commonly used tumor marker. In healthy individuals, CEA levels are normally very low. However, in certain malignant tumors—such as gastric cancer, colorectal cancer, pancreatic cancer, and breast cancer—CEA levels may rise. When the concentration of CEA exceeds the normal reference value of 5.0 ng/mL, there may be an increased risk of having a tumor.

It is important to note that CEA is not a specific tumor marker; therefore, a definitive diagnosis of cancer cannot be made based solely on CEA levels. A comprehensive evaluation combining laboratory tests, imaging studies, and pathological biopsy results is necessary. If a patient is found to have elevated CEA levels, prompt medical consultation is recommended for further investigation and diagnosis to determine the underlying cause.