Carcinoembryonic antigen (CEA) test

What is a Carcinoembryonic antigen test?

A carcinoembryonic antigen test is not a screening test nor is it a diagnostic test. Instead, it is a test that detects the presence of CEA antigen in your blood or other body fluids and determines the effectiveness of anti-cancer treatments. It also ascertains if cancer has spread to the other parts of your body from its primary origin.

What is a Carcinoembryonic antigen?

CEA is a glycoprotein secreted by the epithelium of a growing embryo. The quantity of CEA in the body begins to decline after birth and a healthy adult has only traces of this antigen present. Used as a tumor marker, CEA can be used to determine the success of anti-cancer treatment and to find out if the malignancy has spread to other parts of your body.

Why has my physician asked me to undergo a CEA test?

The levels of CEA rise in the presence of malignancies of the following organs:

– Breast
– Lung
– Thyroid
– Pancreas
– Stomach
– Colon/rectum
– Ovaries
– Liver

CEA tests cannot be used to diagnose or detect cancer for the first time due to a lack of accuracy. Some non-malignant conditions tend to increase the levels of CEA in the body and many people with cancer may not have high CEA levels in their blood or body fluids. Your physician may prescribe a CEA test for you if you already have the diagnosis of malignancy in order to-

– Plan a course of action as far as the treatment is concerned.

– Figure out the extent of the spread of your cancer.

– To monitor the success of treatment (chemotherapy /radiotherapy/surgery).

– To ascertain if the malignancy has had a relapse.

For serial monitoring of CEA to be effective, a baseline value should be jotted down prior to initiating anti-cancer therapy. CEA levels tend to return to normal values within 1-4 months of eradicating the tumor from the body.

What non-cancerous conditions can lead to an increase in CEA?

The levels of carcinoembryonic antigen may be elevated in some non-cancerous disorders including-

– Liver diseases (including cirrhosis)
– Inflammatory bowel diseases (ulcerative colitis and Crohn’s disease)
– Emphysema
– Breast disorders
– Rectal polyps
– Smoking
– Peptic ulcer
– Pancreatitis

Can I undergo a Carcinoembryonic antigen test if I am pregnant?

Yes, you can undergo a CEA test even if you are pregnant or breastfeeding your child.

Can children undergo a Carcinoembryonic antigen test?

Yes, children can undergo the CEA test as it is a safe, risk-free and easy to perform test.

Do I need to fast before a Carcinoembryonic antigen test?

There is no need to fast before undergoing a CEA test. It is a blood test that measures the levels of carcinoembryonic antigen, whose levels are not affected by the intake of food.

How should I prepare for a Carcinoembryonic antigen test?

Although no specific preparations are required before undergoing a CEA test, a few important points should be kept in mind-

– Tell your doctor about your medical history including the medicines or supplements that you might be consuming. Do not forget to tell your doctor if you suffer from a bleeding disorder or are taking blood-thinning medicine (e.g. Aspirin).

– Avoid smoking a few days before the test as smoking may lead to elevated levels of CEA.

– Avoid consuming biotin (an ingredient in many multi-vitamins pills) for up to 72 hours prior to the test. Biotin can affect the results of the test.

– Inform your doctor if you are pregnant at the time of the test. During pregnancy, CEA levels tend to be high.

What are the risks involved?

A carcinoembryonic antigen test is a safe, risk-free and easy to perform test. But as it is a blood test, it does carry a few risks. The test involves inserting a needle in one of your veins on the arm to withdraw a sample of blood. This might lead to a sensation of a prick or a sting. It can also lead to bruising, bleeding, the formation of a hematoma or an infection at the site of the invasion.

When a needle is inserted in your vein, you may also feel dizziness and the sight of blood may unnerve you. It is advisable to look away during this procedure if you are faint-hearted.

What are the contraindications of a Carcinoembryonic antigen test?

There are no absolute contraindications to a carcinoembryonic antigen test. However, if you are suffering from a coagulopathy or are on blood thinners, your physician may avoid making you undergo this test for the fear of a bleeding complication.

How is a Carcinoembryonic antigen test performed?

A carcinoembryonic antigen test is performed as an outpatient procedure. It is a safe, minimally invasive and quick test. No sedation is given. The test can be carried out in a doctor’s office or at a diagnostic center. If you are already admitted to a hospital, this test will be carried out in a hospital setting itself. (The blood sample may then be analyzed in the hospital itself or sent to another laboratory if the facility to test CEA is not available in the concerned hospital). The test involves the following simple steps-

– A technician will apply a tourniquet proximally to the site chosen for venipuncture. This makes the veins more prominent, allowing easier access.

– The area is cleaned with a disinfectant. A sterile needle is used to puncture the vein and draw about 5 ml of blood.

– The pressure is applied to the vein with sterile gauze after the needle is withdrawn.

– The tourniquet is released. The blood sample is collected in a vial. A small bandage is applied over the site from where blood has been drawn.

Apart from blood, CEA levels may also be analyzed in other body fluids, such as-

Cerebrospinal fluid– Sample is taken from the spine.
Peritoneal fluid– Sample is taken from the abdomen.
Pleural fluid– Sample is taken from the lungs.

The procedures for withdrawing samples in the above cases differ from the one explained for a blood test.

How long does the procedure last?

The process of CEA testing does not take more than 5-10 minutes. However, in certain cases, venous access may be difficult to obtain-young children, obese patients and patients belonging to the geriatric age group are a few examples. In these circumstances, more than 1 prick may be required while withdrawing venous blood for sampling-thus increasing the procedure time.

When can I get the results of the test?

You can get the results of a CEA test within 24 hours.

What do the results of my CEA test convey?

A normal result is CEA< 5 nanograms per milliliter. Markedly increased levels of carcinoembryonic antigen (>20 nanograms per milliliter) in a patient with compatible symptoms are strongly indicative of the presence of malignancy and point towards the possibility of metastasis. Pregnant women and chronic smokers have a higher level of CEA in their bodies.

What do the results mean?

If the CEA test has been performed on your body for the first time.

– A low level of CEA may mean that your tumor is small.
– A high level of CEA may mean that the size of your tumor is large or that it has metastasized.

You may also be serially tested (against a baseline value) during your anticancer therapy and the results may be as follows-

– The CEA levels remain high– This may mean that your cancer is not responding to therapy.

– The levels of CEA decrease– This may mean that your tumor is responding to therapy.

– The CEA levels decrease initially, but later increase– This may mean that your cancer has relapsed.

What is the cost of undergoing a Carcinoembryonic antigen test in India?

The cost of undergoing a CEA test ranges from Rs 750-1000. The actual cost depends on the city that you reside in.

What are the advantages and limitations of the CEA test?

What are the other modalities that are used to monitor cancer therapy?

Adequate imaging of the body should be obtained for staging, assessing and monitoring the success of anticancer therapy. These modalities include computed tomography (CT), contrast ultrasound, magnetic resonance imaging (MRI) and positron emission tomography (PET) scanning.