Definition

Carcinoembryonic Antigen (CEA) test measures levels of a specific glycoprotein in the blood known as CEA. First discovered in 1968, CEA was identified while isolating liver tissues affected by gastrointestinal cancer. High CEA levels are typically observed at birth and decrease over time. However, in certain conditions such as cancer, CEA levels can increase significantly.

CEA is often referred to as a tumor marker or tumor antigen. Tumor markers are substances produced by cancer cells and can be detected in blood or bodily fluids. Healthy cells may also produce these substances, but at much lower levels. CEA test helps doctors gather information about cancer and plan treatment strategies.

It is important to note that CEA testing is not typically used as a primary diagnostic tool for cancer due to several limitations, such as elevated CEA levels are not always indicative of cancer, because some cancers may not result in high CEA levels. Other non-cancerous conditions, such as liver, digestive, or respiratory disorders, may also elevate CEA levels.

CEA test commonly uses blood samples to measure CEA levels. However, in rare cases, fluid samples from the spinal cord, chest, or abdomen may be tested. These alternative methods are less frequently performed.

Indications

The CEA test is primarily performed on patients already diagnosed with cancer that affects CEA levels, commonly cancers of the digestive tract. It is typically conducted alongside other tests to evaluate cancer progression, prognosis, and response to treatment.

CEA test helps predict recovery or recurrence and is used to:

• Assess cancer severity before treatment.
• Guide treatment planning prior the therapy.
• Compare CEA levels before and after treatment.
• Monitor treatment efficacy during therapy.
• Detect cancer recurrence or confirm remission after treatment. Regular CEA testing may be necessary to ensure ongoing monitoring and early detection of changes.

Contraindications

CEA test is considered safe, with moderate associated risks. There are no specific contraindications for this procedure. The process of collecting a blood sample is similar to other routine blood tests. Patients should discuss any concerns about the procedure with their doctor.

Preparation Prior to Test

CEA testing does not require special preparation or fasting unless other concurrent tests mandate fasting. Patients should inform their doctor about any medical conditions and medications they are taking. Staying calm, hydrated, and stress-free is recommended. If necessary, the doctor may advise discontinuing certain medications before the test.

Test Procedure

The CEA test typically involves collecting a small blood sample. The laboratory staff will clean the arm with an alcohol swab. A sterile syringe is used to draw blood from a vein. Patients may feel slight pain, a prick, or a burning sensation when the needle is inserted or when blood is drawn. Relaxing the arm can help minimize discomfort. The sample is placed into a special tube and sent for analysis.

If the CEA test involves body fluid samples (e.g., spinal or abdominal fluid), the doctor will apply a local anesthetic to numb the area, typically the lower back. They will use a thin needle, often guided by X-ray imaging, to collect the fluid sample.

A blood-based CEA test takes less than 5 minutes, while fluid-based sampling may take up to 30 minutes. Risks are minimal and may include temporary pain, dizziness, or bruising, which generally subside quickly.

Normal and Abnormal Values

Normal range of CEA levels is 0–2.9 ng/mL. The abnormal CEA Levels are above 2.9 ng/mL, with values exceeding 35 ng/mL potentially indicating false positives. Normal value ranges may differ slightly between laboratories. Patients should discuss results with their doctor for accurate interpretation.

Results and Recommendations (Follow-up Tests)

CEA test results are evaluated in conjunction with other diagnostic tests. If you have a test before cancer treatment, the possible test results are:

• Low CEA levels suggest a small tumor that has not spread. However, certain cancers do not produce CEA, necessitating additional tests to determine cancer type and how it spreads.
• High CEA levels indicate the possibility of a larger tumor and/or metastasis. Further tests are required to assess cancer severity and spread.

When using CEA test results to monitor cancer treatment, your doctor will evaluate them in conjunction with previous test results:

• A decrease in CEA levels over time generally suggests that the treatment is effective.
• An increase or persistently gigh CEA values may indicate that the treatment is less effective or that the cancer has recurred. However, these results do not always confirm unsuccessful treatment or cancer recurrence. Additional tests are often required to determine the cause.
• A decrease in CEA levels after treatment followed by a subsequent increase may suggest cancer recurrence. As with persistently high values, further testing is necessary to identify the exact cause.

Consult the Right Doctor

If your CEA test results are abnormal, consult an internist for further diagnosis and appropriate therapy. The doctor may recommend additional tests to clarify the findings before making a definitive diagnosis.

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