Genetic Testing for Cancer in Families: An Expert Q&A

November 6, 2018
Tiffani DeMarco, MS, LCGC

Tiffani A. DeMarco is a licensed and certified genetic counselor and the manager of the cancer genetic counseling program at the Inova Schar Cancer Institute in Northern Virginia. She has over 21 years of clinical experience counseling patients and their families at risk for hereditary cancer.

If your family’s cancer history suggests that you may be at risk of developing a specific type(s) of cancer, your doctor may recommend that you meet with a genetic counselor and explore genetic testing.share on twitter

1.  What is hereditary cancer?

Most cancer begins when genetic changes called mutations occur by chance in our cells during our lifetime. These are called acquired mutations. In families with hereditary cancer, a genetic mutation that increases the risk for developing certain cancers is passed down from 1 generation to the next. This is called a germline mutation. Only a small percentage of cancer is hereditary.  This may also be called inherited cancer.

2. What features of a person’s personal and family history may suggest hereditary cancer?

  • A personal history of a cancer diagnosis before the age of 50

  • At any age, a personal history with:

  • The same or related cancers in 2 or more close family members, such as breast cancer in a mother and her daughter
  • Multiple primary cancers in 1 person, such as colon and stomach cancer or breast cancer that occurs in both breasts

  • Particular ancestry, such as Ashkenazi Jewish ancestry with a personal or family history of breast, ovarian, or pancreatic cancer

3. What is genetic counseling for hereditary cancer?

During genetic counseling, a genetic counselor meets with you to:

  • Review your personal and family history of cancer

  • Create a family tree, also known as a pedigree

  • Provide a personalized cancer risk assessment

  • Discuss whether genetic testing is recommended

  • Provide recommendations for increased cancer screening and prevention

  • Provide psychological support and follow-up

Having limited information about cancer diagnoses in family members or a small family size may make it more difficult to accurately assess your chances of hereditary cancer. However, that shouldn’t stop you from seeing a genetic counselor.

4. What types of genetic tests are available?

A genetic counselor can review with you what type of genetic testing is recommended based on your personal and family history and any earlier genetic testing you may have had. Types of genetic testing include:

  • A multi-gene panel: This type of testing allows for the analysis of many genes at 1 time. Because several different genes can cause the same or related cancers, this type of testing is often recommended.

  • Site-specific testing: This type of testing may be recommended if a family member had genetic testing that identified a specific mutation.

5. What’s the difference between testing performed on a tumor and testing performed on a blood or saliva sample?

Genetic testing performed on a tumor sample is called somatic testing. It’s limited to mutations within the tumor that are not inherited. Genetic testing that looks for the possibility of inherited mutations that may be passed down within a family is typically performed on a saliva or blood sample. This is called germline testing.

6. What are the possible genetic test results?

  • Positive: This means that testing found a gene mutation known to increase the risk for developing a certain type or types of cancer. If your genetic test result is positive, your family members are at risk for having inherited the mutation. 

  • Negative: This means that testing did not find a mutation in any of the genes included in the test.

  • Inconclusive or a variant of uncertain significance: This means that testing found a change in 1 or more of the genes included on the test, but it’s not clear if that change causes an increased risk for cancer or not.

If you previously had genetic testing that only included 1 or a few genes and your result was negative or inconclusive, additional genetic testing may be recommended.

7. What would a positive genetic test result tell me about my risk for cancer?

If you haven’t previously been diagnosed with cancer, you may learn that you have an increased risk for developing a certain type(s) of cancer. If you previously had cancer, you may learn that you’re at increased risk for developing another cancer. Also, if you’ve had cancer, your positive genetic test result may help your doctor determine what type of treatment may be the most effective for you. Research on these types of targeted treatments is ongoing. 

8. Will my insurance company cover the cost of genetic testing?

Genetic testing for hereditary cancer is often covered by insurance. You and the genetic counselor should discuss your specific options based on your specific insurance coverage before starting the test. There are options available for paying out of pocket. The cost of genetic testing for hereditary cancer is typically a few hundred dollars.

9. Can my insurance company discriminate against me if I have genetic testing?

A federal law known as the Genetic Information Nondiscrimination Act, or GINA, prohibits employers and health insurers from using genetic information, including your family history and genetic test results, to discriminate against you. However, current federal laws don’t prohibit the use of family history or genetic test results by life, long-term care, or disability insurers. Talk with a genetic counselor to get more information on GINA, read more in this article, or visit (Please note that this link takes you to a separate, independent website.)

10. Where can I learn more about my risk of hereditary cancer?

If you’re concerned about your personal and family history of cancer, ask your doctor for a referral to a genetic counselor. Or you can visit the website of the National Society of Genetic Counselors to find one in your area.