What is Carcinoembryonic Antigen?
Cea, or carcinoembryonic antigen, is a glycoprotein found on the surface of certain tumor cells and can be detected in the blood. CEA belongs to the group of oncofetal antigens and is best known for its role in oncology, where it is used as a tumor marker to evaluate and monitor the treatment of various types of cancer, especially colorectal cancer. It is produced by a variety of cells, including enterocytes in the intestines, and can also be present at low levels in healthy individuals.
Why is analysis carried out by CEA?
Carcinoembryonic antigen analysis is primarily performed to identify and monitor treatment of colorectal cancer, but elevated levels of CEA can also be seen in other tumors such as lung cancer, pancreatic cancer and breast cancer. However, CEA is not specific for any single form of cancer, which means that elevated concentrations of carcinoembryonic antigen can indicate several different conditions.
Other forms of cancer where CEA may be elevated:
- Colorectal cancer (90% of cases)
- Pancreatic cancer (80% of cases)
- Lung cancer (about 50% of cases)
- Breast cancer (55% of cases)
- Stomach cancer (ventricular cancer)
- Medullary thyroid cancer
Benign conditions where CEA may be elevated:
- Liver cirrhosis
- Ulcerative colitis
- Pulmonary emphysema
- Cholecystitis
- Inflammatory diseases of the abdominal cavity
- Chronic inflammatory conditions
- Smoking
Cea is therefore not a tumor marker that is specific for a certain type of cancer. Elevated levels can occur in several different forms of cancer and also in non-malignant conditions. Therefore, the CEA assay should always be interpreted in conjunction with other clinical findings and diagnostic tests. By measuring the concentration of CEA, the doctor can obtain important information that can be used as part of diagnostics and treatment.
- Identify cancer risk: If a patient presents with symptoms such as abdominal pain, weight loss, or changes in bowel habits, a CEA test can help determine if further investigations are needed.
- Follow the effect of the treatment: During and after treatment for cancer, CEA levels are measured regularly to see how well the treatment is working. A decrease in CEA levels often indicates that the treatment is effective.
- Detect recurrence early: If CEA levels start to rise again after stopping treatment, it may be an early sign that the cancer has returned.
It is important to note that elevated CEA levels do not always mean that you have cancer. Levels may also be elevated in other conditions, including benign diseases. Therefore, the CEA test is most often used together with other examinations, such as diagnostic imaging, to provide a more complete picture of the patient's state of health. The test is a valuable tool for doctors to make informed decisions about diagnosis and treatment.
Interpretation of test results and reference value
CEA test results can vary by up to 20-30% due to sampling variability, method error, and individual differences. Only changes of 20% or more are considered clinically significant; minor changes should be interpreted with caution and confirmed with repeat sampling. Because different laboratories may use different test methods, results from different sites may be difficult to directly compare, which is important to consider when referring between different hospitals or laboratories. Elevated CEA values can be due to several benign conditions, such as cirrhosis of the liver, ulcerative colitis, pulmonary emphysema, cholecystitis and also in inflammatory conditions.
Reference interval for Carcinoembryonic antigen:
- Sample response below 5 ng/mL
This means that CEA values below 5 ng/mL are considered to be within the normal range. Values above this may indicate the need for further investigation, but must always be interpreted in connection with clinical findings and possible symptoms.