Carcinoembryonic Antigen (CEA) Test

Carcinoembryonic Antigen (CEA) is a set of glycoproteins involved in cell adhesion (the ability of the body cell to stick to other cells). It is a type of substance through which doctors can detect a tumour in the patient’s body.

CEA is produced right when a baby is growing inside its mother and disappears after birth. Its value is very low at birth or not present. Ideally, it should not be present at all. However, in normal healthy tissues, it can be present in very low levels. The CEA levels may be increased in chronic smokers.

CEA are proteins that are produced by some types of cancer. The CEA test is used to determine the level of efficacy provided by a given treatment employed to detect cancer. In simple words, a CEA test is used to determine how well a particular treatment works in certain types of cancer, specifically colon cancer (cancer in the large intestine).

It can detect colorectal cancer in patients with a sensitivity of ~80%. However, the CEA blood test is not reliable for detecting cancer, especially during the early stages. Most types of cancers do not show high CEA levels.

Colorectal cancer is a colon or rectum cancer situated at the lower end of the digestive tract. Most of the time, it starts as a growth on the inner lining of the colon or rectum. These growths are known as polyps. However, Colorectal cancer might not show signs in the early stages.

High risks for colorectal cancer:

• Family history of the disease
• Animal-containing fat diet
• Inflammatory bowel disease
• Tobacco use

CEA test is used for the diagnosis of early detection of liver metastasis (cancer spreading to the liver) in patients with diagnosed colorectal cancer. Despite this, there is very little evidence to believe that the quality of life of a colorectal patient with cancer can be improved, even with early detection and screening.

It is present in around 70 to 80 per cent of advanced colon cancers, but only in about 25 per cent of early-stage colon tumours. Currently, the most useful application of CEA is in the detection of liver metastasis from colorectal cancers.

Besides colorectal cancer, other conditions in which CEA levels are high are:

• Chronic or long-term smoking
• Liver disease
• Inflammatory bowel disease (Crohn’s disease and Ulcerative colitis)  
• Ulcers
• Cirrhosis
• Hypothyroidism
• COPD (Chronic Obstructive Pulmonary Disease)
• Infection
• Pregnancy

CEA test is also carried out after surgery to check carcinoembryonic antigen levels. This test helps the doctor check how much CEA is still present in the blood, spinal fluid or peritoneal fluid. It is also a method to assess the effectiveness of chemotherapy and radiotherapy in cancer patients.

CEA levels should be monitored closely by repeated testing to prevent a recurrence. If there is a resurgence in the levels of CEA post-treatment, this might indicate the need for surgical re-exploration.

Other names of CEA test

• Carcinoembryonic Ag
• CEA
• Embryonic Carcinoma Antigen
• Carcinoembryonic Antigen
• Carcinoembryonic Antigen Blood Test

What is the purpose of doing a Carcinoembryonic Antigen test?

A CEA test is required for the following:

• To assess the effectiveness of treatment of colon cancer or other types of cancer.
• To find out the stage of cancer.
• After surgery monitor whether the disease has recurred.

The CEA test results are based on the analysis of the blood samples. After collecting the blood sample, the laboratory processes the blood to obtain serum and the serum is used for detecting CEA. In some patients, fluid from the spine, abdomen or lungs, respectively, is used to detect CEA.

Test Preparation

The CEA test is a blood test that does not require fasting before the collection of the blood sample. Also, smoking may increase CEA levels, so it is advised not to smoke before the test is performed.

The usual way to collect a blood sample is by drawing it from one of the veins. This vein is usually the most prominent one in the forearm of a person. The patient might feel a pricking sensation or pain while inserting the needle. The entire procedure takes not more than five minutes.

Sometimes the doctors may collect fluid from other body areas such as cerebrospinal, peritoneal or pleural (i.e., from the spine, abdomen or lungs, respectively).

Test inclusions: What parameters are included?

The CEA test only checks the CEA levels in the blood to monitor the progression of cancers in the digestive tract, breast, lung, reproductive system, urinary system, head and neck, thyroid, lymphoma and melanoma.

How frequently should you take this test?

A single result for CEA levels is not enough to monitor patients’ condition. Therefore, the doctor will recommend patients for CEA tests before, during and after the treatment.

• CEA test is initially carried out when the patient’s symptoms point towards cancer.
• The doctor will advise their patients regularly to check if the cancer treatments such as chemotherapy, radiation and/or surgery are working.
• Lastly, the doctors will suggest a CEA test post-treatment to check if the cancer has come back.

The time gap between two CEA tests varies from patient to patient. For example, in patients with Stage 2 or 3 colon cancer, the doctor will recommend a CEA test every three months. Also, the patient will need to do this test up to three years post-surgery. However, if cancer has spread to other body parts, the doctor will recommend a CEA test every month.

Colorectal cancer, Lung cancer, Breast cancer, Liver cancer

• CEA is very low or not present at birth.
• CEA can be present in adults in lower amounts.
• CEA levels are slightly higher in smokers.
• CEA levels decline about 6-12 weeks after surgery. However, if they still do not go down, this is indicative of a recurrence of cancer.

• In smokers, slightly higher values may be considered normal (0 to 5 ng/mL), which is an indicator of cancer or inflammatory conditions in non-smokers. A low level of CEA indicates that cancer has still not spread to other body parts.
• Higher values of CES (>20.0 ng/ml) indicate that cancer has metastasized, i.e., cancer has spread from its original place to other parts of the body.
• Some individuals can have CEA values very high (more than 100 ng/ml). This indicates that cancer has spread to the pleural cavity (a thin tissue layer that surrounds the lungs), peritoneal cavity (a layer of tissues that cover abdominal organs) and central nervous system (brain and spinal cord).