Biomarker testing studies cancer cells found in tumor tissue (or blood). Every cancer is different. Biomarker testing can help doctors learn more about the cancer you have and how to treat it. Biomarkers are chemical changes (differences) in the body’s cells and in cancer cells. Patterns in biomarkers may show why your cancer started or what could cause it to grow. Biomarker testing looks for these patterns..
There are many terms doctors may use when referring to biomarker testing. They might not use the exact words "biomarker testing" Instead, they might talk to you about genomic tumor testing, molecular testing, next generation sequencing (NGS) or tumor profiling.
What do genes have to do with cancer?
Cancer is caused by certain changes to genes (called variants) that control the way our cells function, especially how they grow and divide.
Genes are small pieces of DNA. They have instructions for how cells should function, and they can contain information about inherited traits such as height and eye color, as well as susceptibility to certain diseases. Genes can change, and a change in a gene is called a variant. Some variants can lead to cancer. There are two types of variants: those that happen in our lifetime (acquired variants) and those that are passed down through families (inherited variants).
Gene variants that develop during your lifetime are acquired variants. They occur as you get older and are the result of the wear and tear of life, the environment around you, and sometimes, lifestyle choices. You do not inherit these variants from your parents and you cannot pass them on to children. Acquired variants are not found in all your cells - sometimes, there may be acquired variants in just cancer cells. These can affect how cancer grows and spreads.
Most biomarker testing is looking at acquired variants in the tumor cell, or other markers of a variant.
Some variants are passed down through families; they are inherited. These variants came from your parents and can be passed on to your biological children. Some inherited variants may increase your risk of getting cancer. You may hear them described as genes that cause cancer. In fact, it is the change or variant in the gene — not the gene itself — that can increase the risk of cancer.
Genetic testing, or hereditary testing, looks at inherited variants that may put you at an increased risk of developing cancer.
Why is biomarker testing done?
Biomarker testing is used to find variants or other biomarkers that exist in cancer cells. Some of these variants may play an important role in how the cancer grows, spreads, and responds to treatment. Therefore, biomarker test results can sometimes help doctors choose the right medicines to treat your cancer. These are called “targeted therapies” or “immunotherapies.” That is because certain biomarkers can be “targeted” with these treatments.
This approach is a change from the past. For example, years ago, everyone with stage three lung cancer received the same treatment. It probably included some combination of surgery, chemotherapy, and radiation. Today, doctors know more about cancer, including what causes cancer to grow and divide uncontrollably. Doctors are now able to use information about what’s going on inside cancer cells to learn the best way to treat the disease.
Not everyone who has biomarker testing will have a targeted treatment to try. Some targeted treatments are only available through clinical trials.
Biomarker testing may also tell more about a person’s prognosis (how cancer may progress).
How is biomarker testing done?
Biomarker testing requires a piece of tumor tissue or blood that contains cancer cells. You might have had a biopsy done to diagnose your cancer. If you did, tumor tissue may be available for biomarker testing. If you didn’t have a biopsy, one may be needed. You may also need to have your blood drawn. A blood sample is sometimes needed for biomarker testing when there is not enough tissue or a biopsy is not possible. Your cancer care team will sort out what is needed and arrange for samples to be sent for biomarker testing. Your doctor will receive a results report on the findings and will discuss those with you. You and your doctor will then decide how to use the information to guide your care.
What are the benefits of biomarker testing?
The results of biomarker testing may provide information on how your cancer is expected to act and may help you and your doctor decide how to treat your cancer.
Are there risks to biomarker testing?
There is a possibility that knowing the results of your biomarker test may cause you to feel anxious, disappointed, or upset. This is because one or more of the following things could happen:
The test result may not be helpful in deciding which medicines to use.
The test result may identify genomic biomarkers that have uncertain meaning or significance for your treatment.
The test result may identify genomic biomarkers that cannot be treated.
The test result may suggest a medicine that is not covered by your insurance.
The test result may suggest a clinical trial that is only available at a hospital a distance from your home.
The test result may suggest you have a genomic variant that you inherited from one of your parents. If your doctor is concerned about this, you may need another blood draw for hereditary genetic testing. Your doctor sometimes orders this test, or you may be referred to a genetic counselor.
If an inherited variant is found, some of your relatives may have inherited this variant and may be at an increased risk for cancer.
Does everyone with cancer need biomarker testing?
No. Some cancers do not have biomarkers that will affect a person’s treatment at this time, so testing would not be useful. Sometimes, there is not enough tumor tissue to do testing. Sometimes, standard cancer treatment (like chemotherapy or radiation therapy) is the best option and targeted treatment is not needed. You can ask your cancer care team if biomarker testing should be part of your treatment plan.
Is it ok to ask the cancer care team questions?
Yes. Questions help you and your cancer care team learn and discuss what’s important to you.
Below are some questions that can kick off a conversation about biomarker testing:.
What biomarker testing is recommended for the type of cancer that I have?
Have these tests been done? If so, what did they show?
Can I get a copy of my test results?.
How will this testing change my treatment?
Who do I talk to if I have questions about my results?
What steps do I need to take to get any additional recommended testing?
Would it help us to get a second opinion about my results?
How do I learn more about biomarker testing and targeted treatments?