What is the carcinoembryonic antigen (CEA) blood test?
The CEA blood test measures the level of a specific protein called carcinoembryonic antigen (CEA) in the blood. This protein is normally formed during foetal development and will usually decrease to very low levels with age or even disappear entirely.
As such, if this protein suddenly increases in your blood, it may indicate the presence of a medical condition, such as cancer. Blood tests for carcinoembryonic antigen are widely accessible in Singapore and can be performed in private clinics, polyclinics, or hospitals.
What is the CEA test used for?
Although an elevated CEA level can indicate the presence of cancer, it is not used as a screening tool. This is because an elevated CEA level can be seen in various non-cancerous conditions and not specific to any one type of cancer, which can result in incorrect diagnosis.
Instead, this test is usually used as part of ongoing healthcare management to help healthcare providers in the following ways:
Monitor and plan cancer treatment
A CEA blood test helps healthcare providers monitor how well cancer treatment, such as chemotherapy or surgery, is working. If CEA levels drop, it can indicate that the treatment is working well. However, if the levels are elevated, it may be a sign that the treatment is ineffective.
Having this information can help your healthcare provider adjust the treatment plan accordingly.
Detecting cancer recurrence
After you have completed cancer treatment, elevated levels of CEA in the blood may indicate that the cancer has recurred.
Cancer staging
The CEA blood test can provide information about how far a cancer has spread (cancer staging). Higher CEA levels are often associated with advanced stages of cancer.
This information helps healthcare providers predict the likelihood of treatment success and tailor individual treatment plans.
Conduct further investigation after initial diagnosis
A healthcare provider typically uses a CEA blood test to further investigate a cancer shortly after diagnosis. It is most commonly used for colorectal cancer, but it may also be used for other cancers that can raise CEA levels, including:
Prostate cancer
Lung cancer
Liver cancer
Pancreatic cancer
Thyroid cancer
If your test results show high CEA levels, your healthcare provider will usually perform additional tests to improve diagnostic accuracy and guide treatment decisions. These additional tests may include a CT scan or biopsy (a procedure to collect tissue samples for further examination).
To find out more about whether the CEA blood test is suitable for your medical conditions, request an appointment with Thomson Medical. Our specialists can provide a personalised recommendation and guide you through the health screening process.
What to expect during a CEA test?
Before the procedure, there's no special preparation you need to do. However, if you're currently medicated or smoking regularly, inform your healthcare provider beforehand, as these factors can artificially elevate CEA levels.
The test itself is a simple blood draw, usually taken from a vein in your arm. In rare cases, samples may be taken from other parts of the body, such as the spine, chest, or abdomen. In these instances, a thin needle is inserted into the chest or lower back instead to take a sample of body fluid.
Once the sample is collected, the needle is removed, and a piece of gauze and a bandage will be placed over the puncture site. Afterwards, your body fluid or blood sample is sent to a lab for analysis, with results usually available within a few days.
What do the results mean?
Based on your CEA blood test results, your healthcare provider can determine if your CEA levels are normal or elevated. The CEA test is measured in nanograms per millilitre (ng/mL), with a normal range of 0-2.9 ng/mL for non-smokers and 0-5 ng/mL for smokers.
If your results are within the normal range, this may indicate a small tumour that has not spread. In addition, a significant decrease in CEA levels during treatment indicates that ongoing cancer treatment is effective.
On the other hand, a high CEA result may indicate a tumour that has spread to other parts of the body, a recurrence of cancer, or a sign that current cancer treatment is ineffective. However, high CEA levels don’t necessarily mean you have cancer but can also be caused by non-cancerous medical conditions, such as:
Inflammatory bowel disease (IBD)
Pancreatitis (inflammation of the pancreas)
Liver disease
Lung disease
Gastritis (inflammation of your stomach)
Stomach ulcers (open sore in the lining of the stomach)
Chronic obstructive pulmonary disease (inflammation of the lung that causes breathing difficulties)
Diverticulitis (inflammation that causes bulging pouches in the wall of the large intestine)
Breast cysts (fluid-filled sacs inside the breast)
Diabetes
Accuracy of test results
While the CEA test is useful for monitoring cancer, it is not suitable for early diagnosis due to several factors, such as:
Not all cancers elevate CEA levels
Some cancers that typically cause high CEA levels may not always do so, meaning a normal result does not rule out cancer.
Noncancerous conditions can raise CEA levels
Elevated CEA levels can result from noncancerous conditions like liver disease or breast cysts, making it impossible to definitively confirm the presence of cancer based solely on CEA test results.
Early-stage cancers may go undetected
Early-stage cancers frequently produce insufficient CEA to detect, which could lead to false negative test results despite the presence of cancer.
If your CEA levels are higher than 2.9 ng/mL for non-smokers and 5 ng/mL for smokers, don't hesitate to consult a doctor. Request an appointment with Thomson Medical for recommendations based on your medical conditions and further evaluation.
Are there any risks to the test?
The CEA test is considered a low-risk procedure, as it only requires a sample of blood or bodily fluid to take the measurement. However, as the test involves taking a sample directly from your vein or sometimes from your chest or lower back, you may experience discomfort, such as:
Slight bruising, swelling, or soreness at the punctured site.
Pain around the area where the needle was inserted.
Slight sting during the needle insertion or removal process.
Dizziness due to the withdrawal of blood.
FAQ
What level of CEA indicates cancer?
As of now, there is no specific CEA level that definitely indicates cancer, and reference ranges may vary slightly between laboratories. However, CEA levels below 2.5 ng/mL for non-smokers and 5 ng/mL for smokers are generally considered normal.
So, if your test result is higher than this normal range, it may indicate cancer progression or recurrence after treatment. However, elevated CEA levels alone cannot diagnose cancer, and further evaluation is required to determine the cause of the elevated CEA levels.
What is CEA-positive cancer?
A CEA-positive cancer refers to cancers that cause elevated levels of the carcinoembryonic antigen, which include:
Colorectal cancer (colon and rectum)
Prostate cancer
Ovarian cancer
Lung cancer
Thyroid cancer
Liver cancer
Pancreatic cancer
Breast cancer
What happens when my CEA level is high?
If your CEA blood test shows elevated levels, it can indicate various conditions, such as:
Ineffective cancer treatment plan.
Cancer recurrence after treatment has concluded.
A large tumour in the body that has spread into other parts of the body.
How accurate is a CEA blood test for cancer?
The CEA test is not accurate or reliable enough for diagnosing cancer because of its limitations, such as:
Some cancers that typically cause high CEA levels may not always do so, meaning a normal result does not rule out cancer
Early-stage cancers frequently produce insufficient CEA to detect, which could lead to false negative test results despite the presence of cancer
Non-cancerous conditions (like inflammatory bowel disease, liver disease, and breast cysts) can also raise CEA levels, making it impossible to definitively confirm cancer based solely on CEA test results
Can CEA be high without cancer?
Yes, various non-cancerous conditions can cause elevated CEA levels, such as
Smoking
Liver cirrhosis
Pancreatitis
Inflammatory bowel diseases (e.g., Crohn's disease, ulcerative colitis)
Diabetes
Liver disease
Therefore, a high CEA level does not necessarily mean there is cancer in the body. To confirm the diagnosis, CEA should be performed along with other medical examinations.
The information provided is intended for general guidance only and should not be considered medical advice. For personalised recommendations based on your medical conditions, request an appointment with Thomson Medical.
For more information, contact us:
Thomson Specialists Paragon (Health Screening)
- Mon - Fri: 8.30am - 5.30pm
- Sat: 8.30am - 12.30pm
Call: 6735 0300
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