People with a strong family history of cancer may choose to have genetic testing and counseling to see if they are at increased risk of developing cancer. Genetic testing is unique because the results also provide information about potential cancer risks for family members. For this reason, if you have genetic testing, you are strongly encouraged to consider sharing this information with your relatives.

Sharing positive results with adults

Genetic test results can have a significant medical and emotional affect on the person who had the test, as well as on their family. Most hereditary cancer susceptibility syndromes such as,hereditary breast and ovarian cancer (HBOC), hereditary non-polyposis colorectal cancer (HNPCC), and familial adenomatous polyposis (FAP) are inherited in an autosomal dominant pattern. This means that when a person tests positive for a gene mutation (a change in a person’s genes), their children, siblings, and parents automatically have a 50% chance of having the same mutation. Aunts, uncles, nieces, nephews, and grandparents have a 25% chance of having the mutation.

People who test positive (meaning that the gene mutation is present) for a gene mutation that increases cancer risk have a greater than average risk of developing cancer. If they already have been diagnosed with cancer, they are at increased risk for developing additional cancers. Initial reactions to positive test results can include:

• Grief
  
  
• Anger
  
  
• Anxiety
  
  
• Depression
  
  
• Guilt at possibly passing the mutation to their children
  
  
• Relief to have a reason for the cancer in their family
  
  
• Empowerment to make medical decisions to reduce their cancer risk

The meaning of positive test results for family members and the importance of sharing this information are discussed when a person receives his or her test results. If family members have already discussed their cancer history and genetic testing, sharing test results may be easier.

How much do family members need to know?

The two important pieces of information to share with family members are:

• The specific gene where the mutation was found because many hereditary cancer syndromes are linked to more than one gene.
  
  
• The specific mutation. Gene mutations are commonly designated with a combination of numbers and letters, such as the 187delAG mutation in the BRCA1 gene.

This is the information a laboratory will need to test your family members. It is helpful to provide family members with a copy of your test report.

Relatives who are at risk for having an inherited gene mutation are encouraged to talk with their doctor and meet with a genetic counselor to discuss their cancer risk. A genetic counselor can review screening guidelines and discuss the risks, benefits, and limitations of genetic testing. Your genetic counselor, doctor, or testing laboratory may be able to help locate qualified genetic professionals near your family members and provide written information to share with your family. Learn more about what to expect when meeting with a genetic counselor.

Some strategies for sharing positive test results include:

• Take a family member along to the results disclosure session and have him or her make initial contact with other family members regarding test results. It may be helpful to discuss plans for sharing information before receiving your results.
  
  
• Call, e-mail, or meet face-to-face with family members to discuss the test results. How you choose to discuss test results with family members will depend on your comfort level and relationship with individual family members.
  
  
• Write a letter. This may be easiest for more distant relatives or for family members who are estranged but need to be aware of their potential cancer risk. Your genetic counselor or doctor can help you draft a letter.

Many people choose to have genetic testing so they can share the information with their family members. People who test positive for a gene mutation may feel empowered by having information about cancer risk that past generations did not have and strongly encourage other family members to pursue testing. It is important to understand that not everyone’s reaction to genetic testing is going to be the same, and not all relatives who are at risk will immediately want to have testing. Some family members may feel that undergoing genetic testing will make them more anxious about cancer. Parents may feel guilty about possibly having passed on an increased cancer risk to their children and not want to have that possibility confirmed. Other family members have “survivor’s guilt” if they test negative (the gene mutation is not found), meaning they feel guilty that they were spared this increased cancer risk when their family member was not. Close family members who have a 50% risk of having the gene mutation should be given recommended screening guidelines and followed as though they are at high risk until genetic testing proves otherwise

It is important to be supportive but not pushy when talking to relatives about genetic testing. Everyone should be given the opportunity to undergo testing and to make their own decision about whether to be tested.

Sharing positive test results with children

There are only a few known hereditary cancer syndromes that increase the risk for cancer in young children. Examples include FAP, multiple endocrine neoplasia (MEN) types 1 and type 2 and von Hippel-Lindau syndrome. If a specific gene mutation has been found in the family, it is important for children at risk to have genetic testing. Children who test positive for the mutation will need to begin cancer screening at a young age, and children who test negative for the gene mutation can be spared invasive medical procedures. It is important for you to try to explain to your child, according to their age and maturity level, why he or she needs to have testing. It is also important to let your child know what to expect, since most genetic testing involves drawing blood. A genetic counselor and a medical geneticist (a doctor with training in genetic diseases and conditions) can help you talk with your child about genetic testing and the specific condition in the family. For some conditions, there may be printed materials designed especially for children.

Testing children or adolescents for hereditary cancer syndromes that cause cancer in adults is not recommended. It is important, however, to answer any questions about the family history as openly and honestly as possible. As your children grow older, they may have questions about the family history of cancer. They can be reassured that, despite the family history, there are steps they may be able to take to lower their cancer risk.

Discussing a family history of cancer and positive genetic test results is not always easy. However, by this sharing information with family members, you can take steps to reduce cancer risk and pass this knowledge to the next generation.

More Information

Genetic Testing

The Genetics of Cancer

Genetics

Additional resources

To find a genetic counselor in your area visit these websites:

National Society of Genetic Counselors: www.nsgc.org

National Cancer Institute: www.cancer.gov/search/geneticsservices

Last Updated: July 24, 2009