What Happens During Genetic Testing for Cancer Risk?

The first step in genetic testing is to collect information about your personal and family medical history. This might be done by a genetic counselor or a doctor or nurse trained in genetic counseling.

Personal medical history

You will be asked about your own medical history. This might include:

• Biopsies or surgeries you have had
• Cancer screening tests
• Gynecologic history (for women)
• Lifestyle factors
• Exposure to things that can cause cancer (carcinogens).

If you have been diagnosed with cancer, you will be asked about the type of cancer, whether it was tested for biomarkers, and if you’ve had more than one type of cancer.

Family medical history

A detailed review of your family medical history will also be done. You might be asked to complete a questionnaire before your appointment so you can ask relatives for information. The questionnaire will ask how many relatives have had cancer on your mother’s and father’s side, including the type of cancer and their age when they were diagnosed.

This can help determine if there is a pattern of cancer that might suggest a hereditary cancer syndrome. Try to find medical records or death certificates to confirm cancer in your family whenever possible.

What if I don't know my family's medical history?

If you’re adopted, estranged from your family, or have family members with cancer who have died, you might not have access to your family’s medical history. If this is the case, you’ll want to inform your healthcare team. Having an unknown family history is not the same as having no family history of cancer.

If you’re adopted and the adoption was closed, check to see if your state has laws that allow you to get anonymous medical records from your biological family. If you’re estranged from your family, consider contacting them to ask for details about your family history. Writing a letter or working with your doctor or a mediator to make the request on your behalf might help you obtain the information.

While having a family history of cancer can impact your personal cancer risk, it’s only part of the picture. Your doctor will evaluate your risk based on known information and your overall health and work with you to create a plan. For some people, this might include genetic testing.

Once the information about you and your family has been collected, the genetic counselor will review this information to help determine:

• Your risk of developing cancer
• If genetic testing might be helpful for you
• Any specific gene changes that might be tested for

Your genetic counselor might suggest a test that looks for one or multiple gene changes. They can explain the reasons for their recommendation.

The genetic counselor will explain

• How genes are passed on
• How certain genes can increase cancer risk in families
• The risks, benefits, costs, and limits of genetic testing
• Who in the family should consider being tested.

A person who has or had cancer is often tested first. Then, other family members might be tested later, depending on the results. Sometimes, more than one family member might be offered initial testing.

Things to consider before testing

Before testing, ask your genetic counselor how the results might affect you and your relatives. The counselor can help ease your specific fears and concerns. They can also help you learn how to discuss genetic testing with other family members.

Also, check with your health insurance company to find out if genetic counseling and genetic testing will be covered. Your genetic counselor might be able to help you find out.

Remember that genetic testing is your choice. Even if the counselor recommends you be tested, you still have the right to refuse it.

After risk assessment and genetic counseling, you can decide if you want to have testing. You might want to go home and think about it first, or you might be ready to complete testing that day. If you decide to be tested, you’ll be asked to give your informed consent in writing.

The process of informing you and your family about testing should cover:

• Purpose of the test and why it’s being offered
• Condition being tested for and the test’s accuracy, benefits, and limits
• Other testing options
• How and when results will be shared, what they might show, and possible research use
• How results might affect your care and your family, including screening, treatment, and follow-up decisions
• Counseling and support services
• Your right to refuse
• Genetic discrimination protections and limits

Learn more about informed consent.

Once you’ve signed the consent form, lab tests are done on cells taken from your body. Genetic tests for cancer are typically done on a sample of blood, saliva (spit), cheek cells (from swabbing the inside of your mouth), or skin cells.

Those who have an active blood cancer, such as leukemia, or who have had a bone marrow (stem cell) transplant might need to give a sample other than blood or saliva for accurate results.

Be sure to ask your genetic counselor when to expect the test results, and if you need to schedule a follow-up appointment to discuss them.

The results are often ready 2-4 weeks later. They will be shared with you by phone, a virtual visit, or a scheduled appointment. You might want to ask for a copy of the test result for your records if one is not given to you.

It can help to have a family member with you when you get your results. This might be for emotional support, to help make sure they understand the information, to help with asking questions and taking notes, or to help share results with other family members.

Testing does not always give you clear answers. Genetic counselors are trained to interpret and explain the test results and what they might mean to you and your family. If you don’t have access to a genetic counselor, your healthcare team might be able to explain your results or help you find one.

The results of each test might come back as:

• Positive
• Negative
• Variant of uncertain significance (VUS)

If the result is positive

A positive result means you have one or multiple gene changes that increase your risk for developing certain types of cancer. The test can tell what might happen, but not what will happen. The results of genetic testing do not tell you whether you have cancer.

Coping with emotions

It is normal to be concerned or anxious after learning that you, and potentially other family members, are at increased risk for cancer. You might feel a lot of uncertainty even after the testing is complete. In most cases, there’s no way to know for sure if or when cancer might develop.

Talking with your healthcare provider or genetic counselor can help you cope with your emotions. They can tell you what you might be able to do to lower your risk of these cancers or catch them at an early stage.

How family members might be affected

The genetic counselor will talk to you about whether your family members might also be affected by the gene change. Those family members will need to know what gene change was found so they can decide if they want to be tested for it as well.

You might want to share a copy of your test results with these family members so they can discuss whether to get tested with their healthcare providers.

Learn more about Talking with Family Members About Genetic Testing.

If you have cancer

If you have already been diagnosed with cancer, the result might have found a factor that played a role in causing the cancer. It might also suggest a higher risk for developing other cancers or affect your treatment options for certain types of cancer.

Learn more about Biomarker Tests and Cancer Treatment.

If the result is negative

If the test result is negative, it means the test did not find a change in the genes it tested for. But genetic testing doesn’t look for every possible gene change, so you might still have a gene change that was not tested for or that hasn’t yet been discovered.

Negative results can mean different things, so be sure you understand all the implications of the results.

Depending on your family cancer history, you and other family members might still be considered at high risk of cancer. Talk to your genetic counselor or healthcare team about any steps you can take to decrease your cancer risk.

In families with a known gene change

If you have a family history of a known gene change, knowing you don’t have this gene change can be very comforting. It doesn’t mean you will not get cancer. It just means you might have the same risk as most other people.

If the result is a variant of uncertain significance (VUS)

A VUS is when there is a change in a gene, but it’s not known if this change affects cancer risk. It might simply be a different version of a gene that isn’t seen often enough to be sure, or there might be some other explanation for it.

Typically, no changes to your medical care are recommended when a VUS is found because most have not been found to be harmful once more information on them becomes available.

Your genetic counselor can help you understand what a VUS result might mean for you and your family.

You usually don’t need to have repeat testing if you have a VUS, but staying in contact with the healthcare provider who ordered the test is important in case updates on the VUS become available.