Carcinoembryonic antigen (CEA) is a protein made by gastrointestinal cells. It is mostly made during fetal development (in the womb, before birth), and healthy adult levels are very low. CEA level is often increased in colorectal cancer (bowel cancer) and is considered a tumor marker of colon cancer and rectal cancer. CEA is secreted by colorectal adenocarcinoma cells and measured in the blood.
High CEA level may also be found in patients with some benign (non-cancer) digestive system diseases, like advanced liver disease, pancreatitis, or ulcerative colitis. People who smoke cigarettes may also have increased CEA that is not due to cancer. CEA can be increased in patients with other types of cancer, including breast cancer, lung cancer, and thyroid carcinoma. CEA is not always increased in colorectal cancer, more than 10% of patients with CRC may have normal CEA level.
CEA level is a prognostic biomarker. It gives information about the likely outcome of disease. CEA is also a predictive biomarker. CEA level is a predictor of whether you might benefit from adjuvant chemotherapy after surgery in stage II colorectal cancer (CRC).
CEA is measured in a blood sample. CEA is usually tested at multiple timepoints, such as before, during, and after cancer treatment. This allows comparison of CEA levels over time. While the actual level of CEA in the blood is an important measure, tracking the trend of increasing or decreasing CEA over time provides even more useful information. A carcinoembryonic antigen test may also be called a CEA test, CEA blood test, or CEA assay.
CEA is reported as a number, representing the amount of CEA found in a specific amount of blood. Normal levels are usually less than 3 ng/ml (nanograms per milliliter), though the exact normal cut-off number varies a little bit between laboratories. Heavy smoking can cause levels as high as 5 ng/ml. CEA level may also be normal in colorectal cancer.
If you have a high CEA level
If your CEA increases over time
If your CEA decreases over time
If your CEA is normal
CEA should be tested in all colorectal cancer patients before treatment begins. This lets your healthcare provider compare CEA levels before, during, and after cancer treatment. If you have not had a CEA level test, or are not sure if you have had one, please talk to your healthcare team. CEA level can be a useful biomarker at any cancer stage, and at any point in your cancer treatment.
A biomarker is a piece of information about your health. Biomarkers include your blood pressure, your blood type, and cholesterol or blood sugar levels measured in a blood test. The biomarkers of cancer are also known as tumor markers.