GENETIC TESTINGWHAT EVERYONE SHOULD KNOW

What is Genetic Testing for Cancer?

Genetic testing is the process of looking for mutations (changes) in genes that lead to cancer. Genes are the parts of DNA (deoxyribonucleic acid) that carry the information needed to make proteins, the molecules that control the way our cells function. Genes play a role in determining your risk of developing certain cancers. If you have cancer, its genetic makeup can affect how the cancer grows and what treatments it will be respond to.  

Mutations in genes that may lead to cancer can be either inherited or acquired. Germline (inherited) mutations are passed down from parent to child, and these DNA changes are present throughout the entire body. Acquired mutations (also called somatic mutations) happen during an individual’s lifetime, and can happen in any cell in the body except the germ cells (sperm and egg). Acquired mutations are not passed on to the next generation, and are found only within tumor cells. 

If you have a strong family history of cancer or if you are diagnosed with ovarian cancer, your doctor may suggest genetic counseling and possible testing. Testing for inherited mutations is typically done with a saliva or blood test. In contrast, the tumor itself can be tested for mutations that are either germline or somatic.

Why is Genetic Testing Important in Ovarian Cancer?

• Understanding the genetic makeup of ovarian cancer tumors is important in predicting how the cancer will behave over time (prognosis).
• The genetic makeup of ovarian cancer tumors plays a role in determining which treatments will be most effective.
• Knowing if you have inherited mutations that might put you at risk for other types of cancer, such as breast cancer, can help you take appropriate preventative measures.
• Your siblings and children could also have the same mutation and having this information could be life-saving for them. They can choose to pursue genetic testing as well and get screened for cancer more frequently than the general population. Male relatives can also have these mutations, both potentially passing them on to their children and putting themselves at risk for certain cancers.

Who Should Get Tested?

The Society for Gynecologic Oncology recommends that anyone diagnosed with epithelial ovarian, tubal, and peritoneal cancers should receive genetic counseling and be offered genetic testing. For other types of ovarian cancer, discuss your recommendations for genetic counseling and testing with your cancer care team.

What Genes Does the Test Look For?

There are two general types of genetic testing that are used in ovarian cancer—multigene panels and single gene (BRCA-only) tests. It’s important to talk with your genetic counselor or doctor about which kind of test is best for you.

The benefits of the multigene panels include:

• The ability to detect mutations in the BRCA1/2 genes as well as other genes that might be relevant to tailoring your treatment plan.
• Give you a better understanding of your risk for other cancers.

However, there are also drawbacks of multigene panel testing:

• The results may be complex and difficult to interpret.
• For example, the test can sometimes detect changes or variants of “of undetermined significance”—in other words, DNA changes that scientists aren’t sure about yet. This can cause unnecessary worry or confusion.

Who Provides Genetic Testing?

• A genetic counselor or your doctor can order genetic tests.
• There are at-home genetic tests sold online that do not require a doctor’s order. While at-home tests might be quick and easy to access, they do have risks. For example, the widely known at-home genetic testing brand 23andMe only tests for 3 types of BRCA mutations, while there are hundreds of BRCA mutations that can increase your risk for cancer. This could create a false sense of assurance. At home genetic testing may result in misleading results. If you do choose to take an at-home genetic test, be sure to follow up with your doctor to discuss the results. Your doctor may recommend additional genetic testing to confirm the results.

Learn more about genetic testing for ovarian cancer in this webinar from the Duke Cancer Institute, which includes the perspective of a patient who has been though the genetic testing process.

Genetic Counseling 

Genetic counselors can help you understand more details about genetic testing, with a genetic counselor, you can discuss topics such as:

• Do you have increased risk for ovarian, breast, or other cancers?
• Understanding the benefits and risks of various genetic tests
• What the results from your genetic tests mean, including potential recommendations for increased surveillance for other cancer types
• Who in your family might benefit from genetic testing
• If the genetic tests will be covered by your health insurance 

Learn more about genetic counseling from the Centers for Disease Control and Prevention.