Receiving blood test results can raise questions. A term like “carcinoembryonic antigen” or “CEA” might seem complex. However, understanding what it represents is an important step in self-monitoring your health. This article aims to provide clear and factual information about this marker. We will cover its definition, its role, and how to interpret its value, in collaboration with your healthcare professional.

What is Carcinoembryonic Antigen (CEA)?

Carcinoembryonic antigen (CEA) is a protein belonging to the glycoprotein family. The body naturally produces it during fetal development, mainly in the digestive system. After birth, its production significantly decreases.

In a healthy adult, the liver, pancreas, and intestinal lining cells continue to produce very small amounts of CEA. Therefore, a low concentration of this protein in the blood is considered normal. It participates in cell-to-cell communication, a process essential for the proper functioning of the body.

CEA measurement is relevant because its level can increase significantly in certain medical situations. This is particularly the case for certain cancers, such as colorectal cancer. Doctors therefore use this measurement as an indicator. It can help monitor treatment effectiveness or detect potential recurrence.

This biomarker can be compared to a sensor. It does not directly detect a disease, but it signals cellular changes that warrant special attention.

Why is CEA monitoring relevant?

Understanding CEA is useful because its level is linked to several bodily processes. A variation in its concentration can guide medical decisions regarding monitoring or treatment adjustment.

Since its discovery in 1965, scientific knowledge of this marker has evolved considerably. Initially associated with digestive cancers, research has since shown its relevance in other types of cancer and even in certain benign conditions.

In the context of monitoring, a variation in CEA levels can have implications. For example, a persistent increase may lead a doctor to request additional tests to find the cause. Conversely, a decrease in CEA levels after the start of treatment may indicate that it is effective. This information is one element among others for the medical team.

How to read and understand your test results

On your report, CEA is usually found in the biomarker or tumor marker section. Here are the keys to deciphering this information.

Understanding the indicated values

Your results sheet presents several pieces of data:

• The marker name: “CEA” or “Carcinoembryonic Antigen”.
• Your measured value: it is expressed in nanograms per milliliter (ng/mL).
• Reference values: for a non-smoker, the range is generally between 0 and 5 ng/mL.

Laboratories define these reference values based on statistical data from large healthy populations. They may vary slightly depending on the analysis techniques. It is important to note that smokers often have higher CEA levels, without this being a sign of disease.

Quickly identify important information

For a quick read, you can look for:

• An asterisk or other alert symbol next to your result.
• A value displayed in bold or a different color.
• Any comment from the medical biologist at the bottom of the page.

Finally, it is always recommended to compare your current result with your previous analyses if you have any. The evolution of the level is often more informative than an isolated measurement.

Pathologies associated with marker variation

An elevation in carcinoembryonic antigen (CEA) levels is associated with various medical conditions. The physician interprets this result based on the level of elevation and the overall clinical context.

Significant CEA elevation (> 20 ng/mL)

A very marked increase is often linked to specific pathologies.

Colorectal cancer

Colon or rectal cancer is the most common cause of a significant elevation. Tumor cells can indeed produce this antigen in large quantities. Approximately 70 to 80% of patients with advanced colorectal cancer have elevated CEA. Additional tests usually include a colonoscopy and imaging tests such as a CT scan.

Other cancers

Other types of cancer can also cause a significant increase in CEA. Pancreatic, stomach, lung, breast, or ovarian cancer are examples. The mechanism involves excessive production of the protein by transformed cells. The diagnostic workup is then adapted to the suspected type of cancer.

Moderate CEA elevation (5 to 20 ng/mL)

A more moderate elevation can have cancerous or non-cancerous origins.

Non-cancerous conditions

Several benign diseases can cause a moderate increase. This is the case for chronic inflammatory bowel diseases (IBD), such as Crohn’s disease or ulcerative colitis. Persistent inflammation of the intestinal mucosa stimulates CEA production. Other conditions such as pancreatitis, liver disease (cirrhosis, hepatitis) or pulmonary pathology (chronic bronchitis) can also be responsible.

Smoking

It is essential to remember that smoking is a common cause of moderate and chronic CEA elevation. This increase is not considered pathological.

Causes of a low level

A CEA level below reference values generally has no clinical significance. It is not considered a sign of disease and does not require particular investigations.

Practical advice and medical follow-up

The management and interpretation of a CEA result are always done in consultation with a doctor.

What follow-up schedule?

The monitoring frequency depends on the marker level and the context.

• Slightly elevated CEA (5-10 ng/mL) without obvious cause: a blood test after 1 to 3 months may be suggested.
• Moderately or highly elevated CEA (> 10 ng/mL): a medical consultation is necessary to discuss the next steps and tests to be performed.
• In the context of cancer follow-up: the doctor establishes a personalized and close monitoring schedule.

Nutrition and lifestyle

Although no diet can correct a pathological elevation, a good lifestyle supports overall health.

• Diet: A diet rich in fiber (fruits, vegetables, whole grains) and antioxidants, while limiting red and processed meats, is beneficial for digestive health.
• Smoking cessation: For smokers, quitting smoking often leads to a normalization of CEA levels within a few months.
• Physical activity: Regular activity helps reduce general inflammation in the body.

When to consult a specialist?

It is advisable to consult a doctor quickly if:

• Your CEA level is above 10 ng/mL without a known cause.
• Your level increases progressively over several successive measurements.
• The elevation is accompanied by symptoms (pain, weight loss, etc.).
• You have a personal or family history of cancer.

Simple monitoring may be sufficient if the level is stable, you are a smoker with a slight elevation, or a benign cause has already been identified.

Frequently Asked Questions about CEA

Can CEA be elevated during pregnancy?

Yes, a slight increase in CEA is possible during pregnancy, especially in the first trimester. It is linked to production by fetal tissues and the placenta. Values return to normal after delivery.

Are there daily variations in CEA?

No, CEA levels do not show significant variations during the day. However, it is preferable to perform samplings under similar conditions for better comparison of results over time.

Can certain medications change CEA levels?

Certain treatments can have an influence. For example, some chemotherapies can cause a temporary increase in CEA before a decrease, a sign of treatment effectiveness. It is important to inform your doctor of all medications you are taking.

Can CEA testing be used for cancer screening?

No, doctors do not use CEA testing for cancer screening in the general population, as this indicator lacks sensitivity and specificity. For colorectal cancer screening, healthcare professionals use tests such as colonoscopy or fecal occult blood tests. However, they employ CEA testing as an excellent tool to monitor disease progression in a patient after treatment.

How to interpret elevated CEA after cancer surgery?

After complete removal of a tumor that produced CEA, the level should return to normal within 4 to 6 weeks. Its half-life is approximately 7 days. A new increase after normalization may suggest recurrence and warrants further testing.

Can one have cancer with normal CEA?

Yes, absolutely. Not all tumors produce carcinoembryonic antigen (CEA), especially at an early stage. Therefore, if a patient presents with symptoms, the doctor should never use a normal result alone to rule out a cancer diagnosis.

Conclusion

A patient who understands the role of the CEA marker actively participates in their medical follow-up. A healthcare professional must always interpret this biological indicator taking into account the patient’s overall situation, considering that kinetics—that is, the evolution of the level over time—often informs them more than an isolated value. In parallel, researchers are continuously improving the use of this marker, which promises increasingly personalized and effective monitoring in the future.

Additional resources

• To deepen your knowledge of this blood marker, click here.
• To extend your knowledge and decipher other markers, more articles are available here.

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