Carcinoembryonic Antigen (CEA) Test

The carcinoembryonic antigen (CEA) test is used to measure the amount of carcinoembryonic antigen in a sample of blood. The test is also known as the CEA assay, CEA blood test, or carcinoembryonic antigen test.

CEA is a tumour marker, which is a substance produced by cancerous or normal cells in response to cancer. Although unborn babies generally have high levels of CEA, the levels are very low or even undetectable in healthy adults. CEA testing is mainly used to monitor different types of cancers, such as colorectal, prostate, ovarian, lung, thyroid, liver, pancreatic, and breast cancer. Thus, this test is used by doctors to check how the disease is progressing and to monitor the treatment.

The CEA test is advised with other specific tests if you have the following symptoms of different cancers:

• A change in bowel habits (such as diarrhoea or constipation) or blood in the stool (colorectal cancer).
• Problems urinating or pain in your lower back, hips, and pelvis (prostate cancer).
• Swelling and pain in the abdomen or pelvis (ovarian cancer).
• Chest pain, bad cough, or trouble breathing (lung cancer).
• Lump in the neck (thyroid cancer).
• Lump near the breast or visible changes in the breast (breast cancer).

The test is also highly recommended for individuals who have already been diagnosed with cancers that usually increase CEA levels, including colorectal cancer, prostate cancer, breast cancer, ovarian cancer, lung cancer, and thyroid cancer.

The CEA test is used to monitor and find out whether the treatment is working for the following conditions:

• Colorectal cancer – A cancer that develops in the colon and rectum (part of the digestive system).
• Prostate cancer – This cancer affects the prostate gland (part of the male reproductive system).
• Ovarian cancer –A cancer of the tissues in the ovaries (female reproductive gland).
• Lung cancer – This cancer develops in the lung tissues.
• Thyroid cancer – This is a type of cancer that develops in the thyroid gland.
• Liver cancer – This cancer either starts in the liver or spreads there from another part of the body.
• Pancreatic cancer – A cancer of the pancreatic gland (behind the stomach).
• Breast cancer – A cancer that develops in the breast tissue.

The test can also be used to monitor other conditions in which increased CEA levels are seen. This includes inflammation, cirrhosis (liver disease), and a peptic ulcer (sore in the stomach).

What to Expect Before the Carcinoembryonic Antigen (CEA) Test

No fasting is required for a standalone Carcinoembryonic Antigen (CEA) test. You can eat and drink normally. However, if it is part of a broader package that includes fasting tests, your doctor may advise fasting for 8-12 hours. Avoid strenuous exercise for 24 hours before the test, as intense physical activity can temporarily raise Carcinoembryonic Antigen (CEA) levels and affect interpretation. Always inform your doctor about any ongoing medications.

What to Expect During the Blood Collection

A phlebotomist cleans the skin with an antiseptic, then places an elastic band around your upper arm to make the veins easier to access. A small needle is inserted into the vein; you may feel a brief pinch. Blood is collected into a labelled tube in under a minute.

What to Expect After the Carcinoembryonic Antigen (CEA) Test

A small cotton swab and bandage are placed over the site to stop any minor bleeding. You can return to normal activities immediately. Minor bruising is normal and disappears quickly. If dizzy, sit and rest for a few minutes.

In the CEA test, the primary parameter being measured is:

• The level of carcinoembryonic antigen in a sample of blood.

The normal range of the CEA test is indicated in the table below.

The table below provides a general interpretation of the CEA test results based on whether the levels are low or high.

Note:

• Some cancers do not produce enough CEA. In such cases, the doctor may need to order additional tests.
• Generally, a decrease in CEA levels over time shows that the treatment is working. If CEA levels rise, it may indicate that the treatment is not working. If the levels drop after treatment but then rise again, it means that the cancer has come back.

Like any other medical test, this test also has certain risks and limitations.

Risks:

The CEA test is generally safe and involves minimal risk. You may experience slight pain when the needle is inserted or mild bruising afterwards, which usually resolves spontaneously.

Limitations:

• An increase in CEA levels after treatment does not always mean that the treatment is not working. The doctor will ask for additional tests to find out the underlying cause of high CEA levels.
• Certain conditions affecting the liver, digestion, and breathing can increase CEA levels.

Depending on your symptoms and results, your doctor might recommend certain additional tests to better understand your condition:

• Computed tomography (CT) scans
• Fine needle aspiration
• Karyotype genetic test
• Lactate dehydrogenase (LDH) test
• Sentinel lymph node biopsy
• Tumour marker test
• Colonoscopy
• Sigmoidoscopy

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