Genetic testing looks for changes in the code of your genetic material that may cause disease. It can also look at the changes in your cancer cells. Your genetic code is the information that your body uses to create itself and dictate how each of your cells works.

Genetic testing for cancer checks a child’s genes to:

• Find inherited risks: Some children are born with genetic changes that raise their chance of getting cancer. We call these hereditary cancer syndromes or cancer predisposition syndromes. 
• Understand the cancer: Tests on tumor cells can show gene mutations that drive the cancer to grow. This helps doctors choose the most effective treatments.
• Find new treatments: The COMPASS clinic uses genetic testing to see if your child’s cancer might respond to a targeted therapy.
• Guide family care: If a gene change runs in the family, other relatives may also want to get tested.

In kids with cancer, we use genetic testing to:

• Help explain why a child got cancer
• Help diagnose the exact cancer type or subtype
• Guide treatment choices, such as targeted therapy or immunotherapy
• Learn about the risk that a cancer might come back or spread
• Check if other family members might also be at risk

If your child has a blood disorder, their care team will want to get some genetic testing as well. In these cases, genetic testing has multiple purposes:

• Find the cause: Inherited changes in genes cause sickle cell disease, thalassemia or certain anemias. Testing confirms the diagnosis and specific gene changes.
• Guide treatment: Test results can help doctors choose the right treatments. They’ll help us decide if a child might need a bone marrow transplant or gene therapy.
• Predict disease course: Some gene changes can show how mild or severe the disease might be or if problems could get worse over time.
• Check for related issues: Some genetic conditions that affect the blood may also affect other body parts. They can impact the immune system or your child’s growth. Testing helps doctors keep an eye on those, too.
• Inform family members: If a blood disease is genetic, parents or siblings might also carry the gene. Testing can tell them if they have the gene, too. It can also help guide future family planning.

There are two types of genetic testing that we use for kids with cancer and blood disorders. Germline genetic testing looks for changes in the DNA a child was born with. These changes are in every cell of their body, so we do this testing on a blood or saliva sample.

Somatic (tumor) genetic testing looks for changes found only in the cancer cells. These changes are what drive cancer growth, but they also tell doctors what they can target to kill the cancer. Doctors do this test on tissue from the tumor.

The process of genetic testing typically involves meeting with a genetic counselor. The counselor has a vital role in helping you with genetic testing.

They:

• Explain your testing options: They describe what genetic testing is, what it can show and what it can’t.
• Help you decide: They guide you on whether testing makes sense based on your child’s diagnosis, family history or other factors. Also, they figure out what specific tests you and your child might need.
• Interpret your results: They help families understand the meaning of the test results. If we find a gene change, they walk you through what it means.
• Supports your next steps: If we find a gene change, your counselor can help plan what to do next. It might include watching for related issues, testing other family members or changing your cancer care plan.

Genetic testing is complex and emotional. A genetic counselor helps families:

• Make informed choices
• Understand medical terms
• Cope with uncertainty or worry
• Talk with doctors and coordinate care

Our Cancer Predisposition Program offers genetic testing and care for kids and teens who have:

• A known cancer predisposition syndrome
• A new cancer diagnosis that may be due to an underlying genetic syndrome
• A known family history of a genetic cancer syndrome
• A strong family history of cancers linked to genetic cancer syndromes
• A non-cancer health issue linked to a genetic cancer syndrome

If you’re concerned that your child could fall into any of the above categories, consult your pediatrician. They may refer your child to the Cancer Predisposition Program.

Otherwise, your care team will let you know if they think your child needs germline genetic testing.

Tumor genetic testing may be an option in certain circumstances. It’s standard to get somatic genetic testing at diagnosis for some cancers, including:

• Leukemia
• Brain tumors
• Solid tumors like sarcomas or neuroblastoma

Other times, tumor testing may help plan care if cancer comes back or stops responding to treatment. In these cases, you may consider a clinical trial for targeted therapies through the COMPASS Clinic.

The act of getting a genetic test is very straightforward. We typically do a germline genetic test using a blood or saliva sample. For a somatic genetic test, we’ll usually use a tissue sample from the latest biopsy or surgery. In some cases, we may need to perform a new biopsy.

If your child may have a genetic cancer syndrome, they’ll see the care team at the Cancer Predisposition Program. Our genetic counselor will talk with you about the risks and benefits of genetic testing. They’ll walk you through the available tests.

Once test results are available, they will help you understand your child’s long-term risk of developing cancer. They’ll work with you to create a plan for ongoing monitoring, testing and care.