CEA (Carcinoembryonic Antigen) Test

Although CEA is a tumour marker, lack of specificity renders it unsuitable for screening or confirming the diagnosis of a particular type of cancer. Nonetheless, it is helpful in evaluating an individual’s response to cancer therapy.

CEA is used:

• For monitoring the treatment for colon cancer
• As a marker for cancers of the medullary thyroid, rectum, lung, breast, ovary, stomach and liver
• To evaluate body fluids, apart from blood, for the spread of cancer into the chest (pleural) and abdominal cavity (peritoneal cavity)

This test is performed before commencing cancer therapy to know the ‘baseline values’ of CEA. Further, it is evaluated sequentially to check for response to the therapy, progression of the disease or recurrence.

Occasionally, a CEA test is conducted when there is a suspicion of cancer but not a confirmation of the diagnosis. In such cases, the elevation of CEA hints towards a hidden cancer.

Usually, no special precautions are required for evaluating CEA levels.

It is a simple test that takes less than five minutes. An experienced laboratory specialist will withdraw a blood sample from a vein in your arm by inserting a sterile needle. A small quantity of blood will be collected into a sterile vial or a test tube. A momentary pricking pain is felt when the needle goes in the vein.

There is a minimal risk of pain, light-headedness and bruising at the site of injection. However, at most times, these symptoms disappear quickly. Rarely, an infection may occur at the site of withdrawal of blood.

In certain special situations, when metastasis of cancer is suspected in body cavities (such as abdomen or chest), a small sample of body fluid is extracted using a syringe and needle. The commonly evaluated fluids are cerebrospinal fluid (CSF), peritoneal fluid and pleural fluid.

CEA levels are evaluated as nanograms per millilitre (ng/mL).

Normal results: CEA levels less than or equal to 3 ng/mL are considered normal.

Abnormal results: High levels of CEA indicate cancer but do not point out the specific type of cancer; thus, it is used as a tool to assess the following:

• Response to therapy: CEA levels are evaluated before commencing cancer therapy and thereafter at regular intervals to monitor it. If CEA levels remain high despite the treatment, it indicates no response or poor response to the therapy. However, if CEA levels start dropping, it indicates that cancer is responding to therapy
• Staging: Low or slightly elevated CEA levels in cancer indicate an early-stage tumour, whereas high levels are indicative of advanced cancer or a large tumour
• Recurrence: CEA levels, once decreased after the therapy, when start rising again, indicate recurrence of cancer
• Metastasis: When metastasis to the body cavity is suspected, CEA levels rise in body fluids as well. If cancer has spread to the nervous system, CEA can be detected at higher concentrations in the CSF. If it has spread to the abdomen, CEA is  detected in the peritoneal fluid, and if it has spread to the chest, CEA is detected in the pleural fluid. Thus, it becomes an indicator of metastasis

CEA levels can increase in certain noncancerous disease conditions, such as inflammation, cirrhosis (liver disease), ulcerative colitis, peptic ulcer, emphysema, rectal polyps and benign breast disease. It is also found in higher concentrations in smokers. Therefore, it is not used as a diagnostic or screening tool owing to the poor specificity.

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational perspective and is in no way a substitute for medical advice from a qualified doctor.