What are tumor marker tests?

These tests look for tumor markers, which are sometimes called cancer markers. Tumor markers are substances that are often made by cancer cells or by normal cells in response to cancer. For example, some tumor markers are proteins that certain cancer cells make in larger amounts than normal cells do. Changes in the genes and other parts of tumor cells can be tumor markers, too.

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.

Tumor marker tests are mainly used after you have a cancer diagnosis. The test results may help answer important questions about your cancer, such as:

• How fast is the cancer growing?
• What type of treatment is most likely to help?
• Is the treatment really working?
• Has cancer come back after treatment?

Not all cancers have known tumor markers. And the tumor markers that are known don't provide perfect 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.

But even with these limits, tumor marker testing can often give a more complete picture of your cancer when they are used along with the results of other tests and exams.

What are they used for?

Tumor marker tests are mainly used to learn more about a known cancer. But in certain cases, they may be used to screen for cancer or to help diagnose the disease.

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 after treatment or cancer that comes back after treatment.

Some tumor marker tests that use body fluids (mainly blood or urine) have a limited role in screening 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
• 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. Below are some of the most common types of tumor markers and how they are used. Some tumor markers are linked with only one type of cancer. Others are linked with many different types of cancers:

What happens during a tumor marker test?

Blood tests are the most common type of tumor marker tests. 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: Your health care provider will tell you how to provide your sample.

For a biopsy: A provider will remove a small piece of tissue. There are many ways to do a biopsy, depending on where the sample is located. A biopsy of your skin may be done by cutting or scraping the area. A biopsy of tissue from inside your body may use a special needle to remove a sample or a small incision (cut) to remove all or part of a suspicious area.

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 biopsy site. You may also have a little discomfort for a day or two.

What do the results mean?

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.