Carcinoembryonic Antigen (CEA)

Carcinoembryonic antigen (CEA) is a protein that is primarily associated with certain types of cancer. The most common way to measure CEA is through a blood test, although other bodily fluids may be tested as well.

CEA testing is not used to diagnose cancer, but it may assist doctors in predicting how a person’s cancer may be likely to progress, determining treatment effectiveness, and assessing whether or not cancer has returned after treatment.

Purpose of the test

The purpose of a CEA test is to measure the presence and amount of CEA in a patient’s test sample. CEA is a type of tumor marker. A tumor marker is a substance found in the body that may be a sign of cancer or other health conditions.

Testing may be performed for several purposes:

• Estimating cancer prognosis: Prognosis is a prediction of the expected course or outcome of a disease. Doctors may use CEA levels along with other factors such as the stage or extent of a person’s cancer to estimate their prognosis.
• Monitoring cancer treatment: An increase or decrease of CEA levels during treatment for specific types of cancer may reflect whether treatment is working effectively. In the case of cancers of the colon and rectum, for example, a CEA level will generally be taken as a baseline measurement after diagnosis so that it can be compared to future CEA levels taken during treatment.
• Detecting cancer recurrence: Doctors often monitor CEA levels after treatment for some cancers as a way of trying to determine whether cancer has returned. For example, patients with earlier stage colon and rectal cancer have CEA testing every 3 to 6 months for several years after receiving initial treatment.

In addition to colon and rectal cancer, CEA testing may be done in relation to the following types of cancer:

• Breast cancer
• Lung cancer
• Thyroid cancer
• Pancreatic cancer
• Head and neck cancer
• Cancers of the urinary or reproductive tracts

CEA testing is not used for screening, which is looking for cancer in people who have no symptoms. It is also not used for cancer diagnosis because other, noncancerous conditions can cause CEA levels to increase and because not all cancers cause CEA levels to rise.

Noncancerous conditions that can cause CEA levels to rise include stomach ulcers, pancreatitis, smoking, lung infection, inflammatory bowel diseases like ulcerative colitis or diverticulitis, liver scarring, and gallbladder inflammation

What does the test measure?

CEA testing evaluates how much carcinoembryonic antigen is in the blood, spinal fluid, or peritoneal fluid.

CEA is a protein that is normal in developing fetuses but drops to low or nonexistent levels after birth. Because CEA isn’t typically found in adults, its detection can be related to certain cancers or other health problems.

How to get tested

Procedures for collecting samples used for CEA testing are performed in a doctor’s office, hospital, laboratory, or other medical setting after being ordered by a healthcare professional.

Can I take the test at home?

Tests to measure CEA in the blood or other body fluids are not currently available in an at-home test kit.

How much does the test cost?

The cost of CEA testing depends on a variety of factors, such as a patient’s health insurance coverage, where the test is performed, and any additional testing that is conducted at the same time.

Testing may be covered by a health insurance provider. It may be helpful to contact the health insurance provider or hospital conducting the test for more information about out-of-pocket costs that are associated with CEA testing. Some of these costs may include an office visit as well as fees for obtaining and analyzing the test sample.

A CEA test is usually performed on a sample of blood that is taken by needle from a vein in the arm. Occasionally, other bodily fluids such as peritoneal fluid from the abdomen, pleural fluid from around the lungs, or cerebrospinal fluid (CSF) are collected by a healthcare practitioner for testing.

Before the test

No specific preparation is needed prior to obtaining a sample of blood or pleural fluid for CEA testing. Because smoking can increase CEA levels, smokers may be asked to abstain from smoking for a brief period prior to the test.

If a patient’s doctor orders testing on peritoneal fluids or CSF to monitor CEA levels, a patient may be instructed to empty their bladder and bowels before the test.

During the test

When a blood draw is performed, doctors use a needle to remove a sample of the blood from a patient’s arm. Antiseptic is used where the needle will be inserted to prevent infection. Doctors may then use a tourniquet, which is an elastic band tied around the upper part of the arm, or ask patients to clench their fist to make the vein easier to locate.

Once an appropriate vein is located, blood is removed to fill a small test tube. The entire blood draw is typically finished in less than three minutes. Patients may experience a sting when the needle is inserted or removed.

If doctors choose to extract peritoneal or pleural fluids for testing, ultrasound is often used to guide a needle into a patient’s abdomen or back. Cerebrospinal fluid is extracted through a lumbar puncture or spinal tap, which uses a needle and syringe to remove the fluid surrounding the spinal cord.

Patients who receive a lumbar puncture may be asked by their doctors to remain laying for a short period of time after testing to recover. While the procedure itself takes about 30 minutes to complete, patients should plan to rest for several hours afterward to keep fluid from leaking around the location of the puncture.

After the test

While the risks from CEA testing are generally very low, patients who receive a blood test may experience mild side effects, such as minor pain, tenderness, or bruising where the needle was inserted. These symptoms typically go away quickly.

For test samples taken from pleural, peritoneal, or cerebrospinal fluid, patients may experience additional side effects. Depending on how the sample is collected, these side effects can include headaches, dizziness, blood loss, or infection. Rarely, damage can be done to the bowel, bladder, or lungs.

Patients may benefit from talking with their doctor about any concerns they have about the side effects of testing, as well as any restrictions to work or activities after having a CEA test performed.

Receiving test results

Patients can expect to receive the results of their CEA test within a few days as the sample will need to be analyzed in a laboratory. A follow up visit may be scheduled to discuss the findings of the test, or the patient’s doctor may share these results via an online health portal or send them by mail.

In some cases, doctors may wait to share the results of CEA testing until additional testing has been completed so that they may review all of the results at once.

Interpreting test results

CEA test results are reported in either nanograms per milliliter (ng/mL) or micrograms per liter (µg/L). The test report may also include an interpretation of the measurement, such as normal or abnormal.

When interpreting CEA test results, doctors take several factors into account, including the purpose of CEA testing and previous test results.

When CEA is used to help estimate cancer prognosis, doctors consider the results of a CEA test along with imaging tests or other examinations. For some types of cancer, high levels of CEA are associated with a worse prognosis.

Patients receiving cancer treatment may be tested for CEA levels multiple times during and after the course of their treatment. If CEA levels both start and remain high, it could indicate that the cancer is not responding to treatment. If CEA levels are high initially but then decrease, it may show that the treatment is having an effect. CEA levels that start low and later increase can point to cancer that has come back after a patient has completed treatment.

Not all increases in CEA are a sign that cancer has recurred or resisted treatment. It is possible for CEA to be elevated without the growth of cancer. If a CEA test indicates an elevated level, various types of follow-up tests can be used to obtain more information about the likely cause.

Because there are different methods for measuring CEA, it’s best to use the same test method for monitoring levels over time in order to be able to compare test results most effectively.

CEA tests alone are rarely used to determine the stage of cancer or the effectiveness of treatment. For this reason, it is important for patients to discuss the meaning of their CEA test with their doctor who can explain their significance in the context of their unique case.

Questions for your doctor about test results

Patients may want to consider asking their doctor the following questions to better understand their CEA test results:

• What are the results of my CEA test?
• How have my CEA levels changed over time?
• What do these test results mean for my diagnosis or treatment options?
• How often do I need to be tested for CEA?
• Are any follow-up tests appropriate based on my CEA test result?

Sources

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