Biomarker Testing for Cancer

Biomarker tests check your tissue, blood or other fluids for tumor markers (biomarkers). Tumor markers are gene mutations, proteins or other substances that provide information about a cancer diagnosis.

Learning you have cancer is an important first step in getting the right care. But the details unique to you (like the cancer stage and tumor markers) help healthcare providers tailor your treatment plan. Biomarker testing enables “precision medicine” — personalized treatment that fights cancer at the level of molecules.

The results of a biomarker test may help your provider:

• Recommend treatments: Some cancer treatments are designed to work on cancers with certain tumor markers. Treatments include targeted therapy and immunotherapy. Often, these treatments are more successful and involve fewer side effects than standard treatments, like chemotherapy.
• Predict how aggressive a tumor is: Some tumor markers are a sign that a tumor will likely grow fast or come back after treatment. This can help your provider choose how aggressive your treatment should be.
• See if treatment is working: Treatments that destroy cancer cells may lower the biomarker levels. So, a decline may mean that treatments are helping.
• See if the cancer has come back: Signs of cancer at the cell level often show up before symptoms do. If cancer returns, biomarker testing may detect it.
• Predict your chance of recovery: Tumor markers may help your provider predict your response to treatment or chances of a cure.

Biomarker testing isn’t available for all cancer types. And not everyone who has cancer needs it.

But more and more, this testing allows providers to pick the best treatments for fighting cancer.

How does the test work?

A healthcare provider will need to take a sample of tissue, blood or saliva. They’ll do this during a procedure like a:

• Biopsy
• Liquid biopsy (a type of blood test)
• Spit test

The actual biomarker testing happens in a lab. A lab specialist will run tests on the sample and check for tumor markers. The type of test depends on what they’re looking for. For example, they may test for:

• One specific biomarker
• Many biomarkers (sometimes called a multigene or panel test)
• Genetic mutations in healthy cells (this can show if you had a cancer-related gene variation at birth or if you developed it later in life)

Your healthcare provider can explain what the tests are trying to find.

What are the risks of this test?

There aren’t many risks with these tests. Your healthcare provider will explain any side effects before you agree to a procedure that takes a tissue or fluid sample.

What type of results do you get and what do the results mean?

Your results may show that certain treatments are an option for you. You may be eligible for:

• FDA-approved treatments: Treatments approved by the U.S. Food and Drug Administration have been tested and are considered safe and effective for your unique diagnosis.
• Off-label treatments: Off-label treatments aren’t approved for your cancer type. But they’re approved for other cancers with the same tumor marker. This means there’s a chance the treatment may work.
• Clinical trials: You may be able to take part in a study to access a new treatment targeting cancers with a tumor marker you have.

Your results may be about your prognosis (outlook). For example, results may show you have an aggressive cancer. This tells your provider you may need more intensive treatments. It may show that the cancer responds well to treatment, and your outlook may be excellent.

Your provider will explain what your results mean for your treatment options and outlook.

What should I ask my doctor?

Ask your healthcare provider if biomarker testing will be a part of your diagnosis. If it’s not, ask if it’s an option. They can help you understand the risks and the benefits.

Who should get biomarker testing?

For some cancers, biomarker testing is a routine part of diagnosis. For example, if you have breast cancer, your provider will test the cells. The results can show if cancer grows in response to estrogen or a protein called HER2. If so, you can get treatments that block these substances.

Other cancers with routine biomarker testing include colon cancer and lung cancer.

If biomarker testing isn’t a part of routine diagnosis, your healthcare provider may still recommend it if testing opens up possibilities for better treatment options. It all depends on your unique case.

Are biomarker tests worth it?

They could be. Biomarker testing may be well worth it if it helps you access more effective treatments. It can also be worth it if it gives you a clearer idea of how your disease course may play out.

But not all biomarker tests can provide this information. This is why your healthcare provider is your best resource for explaining whether this testing is for you.