Before we begin: Tumor markers tests look for substances in blood or tissues to monitor cancer growth and treatment. They may also help guide cancer treatment. Learn more.
This tutorial walks you through everything you need to know about tumor marker tests. We explain it in plain language, step by step, so whether you are a student, a patient, or simply curious, you will come away with a solid understanding.
We cover what it is, why it matters, how it is diagnosed, and what you can do about it. Key facts are called out along the way.
What are tumor marker tests?
These tests look for tumor markers, which are sometimes called cancer markers. Tumor markers are substances that are made by cancer cells or by normal cells in response to cancer. For example, some cancer cells make certain proteins in larger amounts than normal cells do. These proteins can act as tumor markers because their presence may mean cancerous cells are present.
Certain tumor markers may be found in samples of body fluids, such as blood or urine (pee). Other tumor markers are found in samples of cells that are removed from a tumor during a biopsy.
Not all cancers have known tumor markers, and the tumor markers that are known don’t always provide accurate information. That’s because:
- Some conditions that aren’t cancer may also cause high levels of certain tumor markers. Tumor marker tests can’t tell whether tumor markers come from cancer or from another condition.
- Some people don’t make high levels of the tumor markers that are commonly found in their type of cancer.
What are they used for?
Tumor marker tests are most often used after you have a cancer diagnosis. When used with other tests, tumor markers may help:
- Find out whether cancer has spread to other parts of your body (cancer stage).
- Predict how fast your cancer may grow, the chance of recovery, and whether cancer is likely to return.
- Select the right treatment for your type of cancer. Some treatments work only with cancers that have certain tumor markers. Tumor markers that help plan treatment are also called biomarkers.
- Monitor how well your treatment is working. If tumor marker levels go down, it usually means your treatment is helping.
- Find any cancer that remains or comes back after treatment.
Some tumor marker tests that use body fluids (mainly blood or urine) have a limited role inscreening for certain types of cancer. The tests are mostly used to screen people who:
- Have a high risk for the type of cancer that’s linked to the tumor marker being measured. This could mean a family history of that type of cancer or that you have certain environmental or behavioral risk factors.
- Have symptoms that could be from that type of cancer.
Tumor marker tests that are used to screen for cancer can’t diagnose cancer. If you have a high level of tumor markers, it only means that you’re more likely to have cancer. A biopsy is usually needed to diagnose or rule out cancer.
Tumor marker tests that use cells from a tumor may help diagnose cancer. These “tumor cell markers” are usually removed during a biopsy. They may be used with other tests to confirm a cancer diagnosis and decide on the best treatment.
Why do I need a tumor marker test?
You may need a tumor marker test if you:
- Are currently being treated for cancer.
- Have finished cancer treatment.
- Have a high risk of getting a certain type of cancer because it runs in your family, or you have other conditions that increase your risk.
The type of test you have will depend on your health and health history, cancer diagnosis, and the symptoms you may have.
What happens during a tumor marker test?
Blood tests are the most common type of tumor marker tests. However, urine tests or biopsies are also frequently used to check for tumor markers. A biopsy is a minor procedure that involves removing a small piece of tissue for testing.
For a blood test: A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.
For a urine test: A provider may give you a cleansing wipe, a small container, and instructions for how to use the “clean catch” method to collect your urine sample. It’s important to follow these instructions so that germs from your skin don’t get into the sample:
- Wash your hands with soap and water and dry them.
- Open the container without touching the inside.
- Clean your genital area with the cleansing wipe.
- For a penis, wipe the entire head (end) of the penis. If you have a foreskin, pull it back first.
- For a vagina, separate the labia (the folds of skin around the vagina) and wipe the inner sides from front to back.
- Urinate into the toilet for a few seconds and then stop the flow. Start urinating again, this time into the container. Don’t let the container touch your body.
- Collect at least an ounce or two of urine into the container. The container should have markings to show how much urine is needed.
- Finish urinating into the toilet.
- Put the cap on the container and return it as instructed.
If you have hemorrhoids that bleed or are having your menstrual period, tell your provider before your test.
For a biopsy: A provider will remove a small piece of tissue. There are many ways to do a biopsy. The type of biopsy you have depends on the type of cancer you have and where the tumor is located. In general, a biopsy may be done using:
- A hollow needle inserted through your skin. Imaging tests, such as ultrasound, may be used to guide the needle.
- A fine needle aspiration biopsy uses a very thin needle to remove a sample of cells and/or fluid.
- A core needle biopsy uses a larger needle to remove a sample.
- Surgery. Surgery may be done to remove a sample of tissue (an incisional biopsy). In certain cases, the entire tumor will be removed (an excisional biopsy).
- Endoscopy. This procedure uses a scope to look inside your body. A special tool may be used with a scope to remove a sample of tumor tissue. Different types of endoscopies may be used depending on where the tumor is located.
Will I need to do anything to prepare for the test?
For a blood or urine test: You usually don’t need any special preparations.
For a biopsy: You may need to fast (not eat or drink) for several hours before the procedure.
Talk with your provider if you have any questions about preparing for your test.
Are there any risks to the test?
For a blood test: There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.
For a urine test: There is no risk to a urine test.
For a biopsy: You may have a little bruising or bleeding at the biopsy site. You may also have a little discomfort for a day or two.
What do the results mean?
Your results will vary depending on the kind of tumor marker your provider tested for. Some tumor markers are linked with only one type of cancer. Others are linked to many different types. Some of the most common tumor markers are:
CA (Cancer antigen) 125
Tumor marker for: | ovarian cancer Used to: |
- See if cancer treatment is working
- See if cancer has come back after you’ve finished treatment
CA 15-3 and CA 27-29 (cancer antigens 15-3 and 27-29)
Tumor markers for: | breast cancer Used to: | Monitor treatment in people with advanced breast cancer
PSA (prostate-specific antigen)
Tumor marker for: | prostate cancer Used to: |
- Screen for prostate cancer
- Help diagnose prostate cancer
- Monitor treatment
- Check to see if cancer has come back after you’ve finished treatment
CEA (carcinoembryonic antigen)
Tumor marker for: | colorectal cancer, and cancers of the lung, stomach, thyroid, pancreas, breast, and ovary Used to: |
- See if cancer treatment is working
- See if cancer has come back after you’ve finished treatment
AFP (Alpha-fetoprotein)
Tumor marker for: | liver cancer, and cancers of the ovary or testicles Used to: |
- Help diagnose liver cancer
- Find out if cancer has spread (the stage of cancer)
- See if cancer treatment is working
- Predict chances for recovery
B2M (Beta 2 macroglobulin)
Tumor marker for: | multiple myeloma, some lymphomas, and leukemias Used to: |
- See if cancer treatment is working
- Predict chances for recovery
Your provider will review your tumor marker test results along with other information about your condition. Together, you can discuss how your results affect your diagnosis, treatment, and schedule for future testing.
Learn more about laboratory tests, reference ranges, and understanding results.
Key Takeaways
Understanding tumor marker tests is an important part of taking charge of your health. Here is what to remember:
- Know the signs — Recognizing early symptoms can lead to earlier diagnosis and better outcomes.
- Talk to your provider — If you have concerns or a family history of this condition, bring it up at your next checkup.
- Stay informed — Medical knowledge evolves. Keep learning and asking questions.
- You are not alone — Many people deal with this condition. Support groups and educational resources can help.