You may have heard of the CEA test, or your doctor may have told you to do it. So, what is the CEA test? Why is it done? I know you have a lot of questions like these in your mind. Don't worry, today we will talk about the CEA test in a simple way that you can understand. I know that when you hear things like this, you feel a little scared, but once you know the details, that fear will go away.
What is CEA (Carcinoembryonic Antigen)? Let's understand it simply!
Imagine, we have a special type of protein in our body. This is what we call CEA, or Carcinoembryonic Antigen . This is actually a protein (glycoprotein) with a lot of sugar attached to it. These can be produced by normal cells and some cancer cells.
It is a very strange fact that when we are all born, we have relatively high levels of this CEA in our bodies. As we grow older, that is, as we age, this CEA level gradually decreases. However, in some disease conditions, especially when certain types of cancer develop, the level of CEA in our blood can increase again.
Scientists first discovered CEA in 1968, when they examined parts of colorectal cancer that had metastasized to the liver and parts of the digestive tract of a healthy fetus.
Sometimes CEA is also called a tumor marker or tumor antigen . Tumor markers are substances made by some cancer cells and added to our body fluids (such as blood and urine). But remember, healthy cells also make these tumor markers, but in much smaller amounts. Most healthy people have these in the "normal range." Your lab report may state this as the "normal range," "reference range," or "reference interval."
What types of cancer is the CEA test mainly used for?
This is where many people make a mistake. The CEA test cannot tell for sure whether you have cancer or not. That is, it is not a screening test to find out if you have cancer.
So why is this done? It is mainly used for people who have already been diagnosed with cancer. This is especially important for people with colorectal cancer.
Doctors also use the CEA test in conjunction with other tests to diagnose, treat, and monitor various cancers. For example, it is used in the diagnosis of bladder cancer, breast cancer, lung cancer, ovarian cancer, and thyroid cancer.
Simply put, the CEA test is used to see how a patient is responding to cancer treatment, to see if the disease has come back (relapse), or to find out if the cancer has come back (recurrence). But this test is not used alone. Your doctor uses it in conjunction with a physical examination and, if necessary, imaging tests.
So, in what situations is a CEA test necessary?
As I mentioned before, the CEA test is not used to diagnose cancer. However, if you already have cancer, this test can provide very important information. Your doctor may use the CEA test to:
- See if the cancer has grown or spread to other parts of the body (metastasized).
- Assess how successful cancer treatment is. You may need to have this test done in the following situations:
- Once the disease is diagnosed, it helps to develop a treatment plan (this is called `baseline testing` ).
- During cancer treatment (e.g., see how effective treatments such as chemotherapy, immunotherapy, and radiation therapy are).
- After treatment is completely finished, check to see if the cancer has come back (recurrence).
- After you are diagnosed with cancer, before treatment and/or surgery. Then, during treatment, this test is done once a month or every three months.
- But here's an important thing to note. An increase in CEA levels within 4-6 weeks of starting treatment does not always mean that the treatment has failed, that the disease has recurred, or that the cancer has returned. Your doctor will tell you more about this.
- Once the disease is in remission, you may need to continue to have CEA tests to check for recurrence. Your doctor will decide how often this is done.
How do you do this CEA test?
Most often, the CEA test is done as a blood test . Your doctor or nurse will take a small sample of blood from a vein in your arm. Then, specialists in the lab will examine that blood sample and check the CEA level.
But very rarely, your doctor may also look for CEA levels in other body fluids. For example:
- Peritoneal fluid (fluid taken from the wall of the abdominal cavity)
- Pleural fluid
- The fluid taken from the spinal cord (this is called ``cerebrospinal fluid or CSF'')
In this case, your doctor will use a needle or syringe to take a small sample of fluid. The needle is inserted into your chest or lower back.
How should I prepare for the CEA test?
There is no need to prepare much for this. Your doctor will tell you how to prepare. You may be asked to stop taking certain medications that increase bleeding (such as aspirin) for a few days. Your doctor will explain all of this to you.
What to expect when taking the CEA test?
If CEA is measured in blood:
- A doctor or nurse will insert a small needle into a vein in your arm (usually near your elbow).
- A small bottle (vial) or test tube is connected to it.
- Then a small blood sample is taken. This takes less than five minutes.
If a sample is taken from other body fluids (e.g., spinal fluid):
- First, a local anesthetic is injected into your lower back and chest to numb it.
- Then a needle or syringe is inserted in the correct way.
- Sometimes, an X-ray is used to check if the needle is in the right place.
- Then a sample of either `(CSF),` `(pleural fluid),` or `(peritoneal fluid)` is taken.
This type of test usually takes about 30 minutes. You can go home the same day as the test.
Are there any risks with the CEA test?
CEA tests are generally very safe. However, there is a very small risk of the following during a pleural fluid test:
- There may be some bleeding.
- An infection may occur.
- There may be minor damage to the lungs.
But most people don't experience any complications from a CEA test. Your doctor will explain these risks to you in more detail before the test. So there's nothing to worry about.
What side effects can occur after the CEA test?
If you had a blood test, you may have some slight bruising or swelling where the needle was inserted for two or three days. This is normal.
If a sample of your cerebrospinal fluid (CSF) or abdominal fluid is taken, you may experience minor side effects such as:
- Dizziness
- Headaches
- Lightheadedness
These usually get better within a few days.
What do the results of the CEA test mean?
Your doctor uses the results of the CEA test to learn more about the cancer.
- If the CEA level is low, it may mean that the tumor is small and has not spread to other parts of the body. However, some types of cancer (especially those in places like the brain) do not produce much CEA. In that case, the value of the CEA blood test may be low. In such cases, doctors may also consider scans such as an MRI.
- If the CEA level is high, it can mean that the cancer is large or has spread to other parts of the body. However, keep in mind that CEA levels alone cannot tell you exactly what stage (tumor staging) the cancer is in or whether it has spread to other parts of the body (metastasized).
Your doctor may monitor your CEA levels throughout your cancer treatment. If your CEA levels decrease significantly during treatment, this often indicates that the treatment is working. However, doctors will confirm this with a physical exam and scans.
What is a normal CEA level?
CEA levels are usually reported in nanograms per milliliter (ng/mL) . A normal level is between 0 and 2.9 ng/mL.
Doctors generally consider a CEA level between 0 and 2.9 ng/mL to be normal. However, some research has shown that levels as high as 35 ng/mL can cause false-positive results. This means that CEA can be elevated even without cancer.
This normal range (reference range) may vary slightly between labs, and doctors may consider higher limits depending on the individual patient's condition.
What is the CEA level that indicates cancer?
Here's the important point. There is no specific CEA level that can accurately predict the presence of cancer. As I mentioned earlier, doctors do not use the CEA test to screen for or diagnose cancer. Generally, a CEA level greater than 2.9 `(ng/mL)` is considered abnormal, but it does not always mean that cancer is present.
Can CEA levels be elevated without cancer?
Yes, it definitely can! A high CEA level does not always mean that cancer is present. For example, people who smoke may have higher CEA levels.
CEA levels can also be elevated due to non-cancerous conditions such as:
- Gastritis and stomach ulcers
- Chronic Obstructive Pulmonary Disease (COPD)
- Liver disease, for example cirrhosis, fatty liver, or gallstones
- Diverticulitis is inflammation of the small pouches in the large intestine.
- Diabetes
- Any autoimmune or inflammatory disease
- Inflammatory bowel diseases (e.g. Crohn's disease and ulcerative colitis)
- Hemorrhoids
- Pneumonias (including COVID-19 pneumonia)
Also, people taking certain treatments made from animal materials (e.g., monoclonal antibodies) may also have elevated CEA levels.
So, what are the final things to remember? (Take-Home Message)
Okay, we've talked a lot about the CEA test now. I hope you have a good understanding of it. To summarize:
- CEA is a special protein (glycoprotein) in our body.
- Some types of cancer can cause an increase in CEA levels. However, an increase in CEA levels does not always mean that cancer is present. There are many reasons why CEA can be increased even without cancer.
- The CEA test is not a test to diagnose cancer.
- This is mainly used to see how people who have already been diagnosed with cancer are responding to treatment and to follow up on the disease.
- If you have any questions about your CEA level or the test, talk to your doctor. They will give you the best advice.
Remember, in medicine, one test cannot tell everything. CEA is just one such aid. Your doctor will make the best decisions based on your overall health. Therefore, do not be unnecessarily afraid or anxious. Talk to your doctor about anything and resolve it.
` CEA test, carcinoembryonic antigen, cancer markers, blood tests, cancer treatment, cancer monitoring, tumor markers
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