How to get genetic testing for hereditary cancer risk

There are two types of genetic testing

There are two main types of genetic testing.

Somatic testing is done on the cancer cells themselves to learn about the cancer. This can help doctors plan treatment and predict how well the cancer might respond to treatment.

Germline testing looks for inherited mutations you were born with that put you at a greater risk for cancer.

Who needs genetic testing for cancer?

Genetic testing is most often recommended for patients with certain types of cancer, people with a family history of cancer or people who have a relative with a genetic mutation. The guidelines for genetic testing are always changing, but you’re typically a good candidate for genetic testing if you’ve been diagnosed with:

• Breast cancer at age 50 or younger
• Colon cancer at age 50 or younger
• Ovarian cancer
• Pancreatic cancer
• Metastatic prostate cancer

Your genetic counselor may also suggest genetic testing based on your family cancer history.

This list is not comprehensive. You should talk to your care team to determine if you are a good candidate for genetic testing.

How to map out your family’s cancer history

1. List your blood relatives. Include first-degree relatives (parents, siblings, children) and second-degree relatives (nieces, nephews, aunts, uncles, grandparents). You can also include cousins. Add the current age of each or the age when they died.
2. Add any cancer diagnoses, including the age when they were diagnosed. List details, such as the part of the body where the cancer started and how the cancer was treated (chemotherapy, radiation therapy, surgery).
3. Include any birth defects or genetic disorders that you know.

In general, you may be at risk for an inherited cancer gene mutation if you have one or more first- or second-degree family members who were diagnosed with:

• Cancer before age 50
• The same type of cancer
• Two or more different cancers
• A rare cancer, such as male breast cancer
• A known genetic mutation, such as a BRCA1 or BRCA2 mutation

Discuss your family history with your doctor. Based on your family history, your doctor may refer you to a genetic counselor who may recommend genetic testing.

Some people may want to get genetic testing even if their doctor doesn’t recommend it. Perhaps you’re adopted and don’t know your family history, or you just want to learn as much as you can about potential cancer risks for yourself and family members. You can always request an appointment with a genetic counselor to help you understand if genetic testing would be helpful.

What to expect when you see a genetic counselor

The genetic counselor will review your family medical history and look for signs that may indicate a hereditary risk. We’ll guide you through the process of understanding your family history, genetic risk and deciding if genetic testing is right for you. And if you do test positive for a genetic mutation, we can help you decide how to communicate that to family members and deal with possible changes in family dynamics.

Will my insurance cover genetic testing?

A genetic counselor will discuss with you whether insurance may cover the cost of genetic testing based on your personal and family history.

If you meet the criteria for genetic testing, it is more likely that insurance will cover genetic testing as a benefit. Some people may still have an out-of-pocket cost for genetic testing based on their policy.   

A genetic counselor can discuss affordable testing options if you don't meet the criteria, have a high deductible or are uninsured.

How will I know which tests I need?

We know of more than 80 hereditary gene mutations that can lead to cancer. Testing for all of them can sometimes lead to confusing results.

So, your genetic counselor will decide which genes are most relevant based on your family medical history and personal history.

This could include the BRCA1 and BRCA2 genes that are linked to breast, ovarian, pancreatic and other cancers. It may also include the genes related to Lynch syndrome, which is linked to colorectal, endometrial and other cancers.

Remember: genetic testing does not diagnose cancer. Even if you have an active cancer diagnosis, your genetic testing could come back negative. That’s because genetic testing is not meant to detect cancer. Rather, it helps us understand the overall lifetime risk for you and your family members developing certain types of cancer.

How will the genetic test be administered?

If genetic testing is recommended for you, your genetic counselor will refer you for a blood or saliva test.

It may be done the same day as your appointment, on a different day when you are scheduled for a lab draw, or we may send you a saliva test in the mail, which you will complete at home and send to the genetic testing lab.

If you have a blood cancer like leukemia, or if you’ve had a stem cell transplant using donor stem cells, you’ll get a punch biopsy for genetic testing. This is a minor procedure where a doctor takes a sample of your skin to be used for genetic testing.

We do this because we want to sample healthy tissue. If you have leukemia, we don’t want to sample the blood because that’s where the cancer is, and we expect there to be genetic mutations. Similarly, if you’ve had an allogeneic stem cell transplant, we want to test your genetic information, not the genetic information from your donor. So, the best option would be a skin sample that we send to a lab to test.

What are the possible genetic test results?

One of the biggest benefits of seeing a genetic counselor for your genetic testing is they will prepare you for three main types of results. Your genetic counselor will go over these possibilities before you undergo testing.

Negative

This is the most common result. It means there were no mutations found in any of the genes that were tested. This means that it’s unlikely that your cancer is hereditary or that you are at risk for a hereditary cancer. But your cancer risk may still be higher than others based on your family history of cancer.

Variant of unknown/uncertain significance

This result means that something unique has been found in a gene, but it is not known to be linked to increased cancer risk.

 We usually treat these results as negative until we have more information because, in most cases, we find out there's nothing there to be concerned about.

Positive

This means that a harmful change or mutation was found in one of the genes that was tested. That genetic mutation increases your risk for cancer. Usually, your family members will then be referred for genetic testing as well.

What happens if my test results are positive for a genetic mutation?

If your test results show that you have a genetic mutation that puts you at a higher risk for a specific type of cancer, you will be referred to an oncologist to discuss next steps.

You may need more frequent cancer screenings or be able to make lifestyle changes to reduce your risk. If your risk for cancer is greatly increased by a genetic mutation like BRCA, your doctor may talk with you about risk-reducing surgery.

How will testing positive affect my family’s cancer risks?

Genetic testing is really a family affair. It doesn’t just affect you because your test results may forecast family members’ cancer risks, too.  

If you test positive, there is up to a 50% chance that your children, siblings and parents can also test positive for the same mutation. This can help determine which preventive screenings your family members should have and when they should start getting screened.

Finding out you have a gene mutation does not mean you will definitely get cancer.

And remember, your genetic counselor is here to support you through the entire process. We’ll walk you through your emotions and help you reconcile what we discover. We’re here for you.

Catherine Skefos is a senior genetic counselor in MD Anderson’s Clinical Cancer Genetics Program.

Request an appointment at MD Anderson online or call 1-877-632-6789.