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Genetic Testing


Cancer is a common disease, and many families have at least a few members who have had cancer. While cancers are often caused by a cancer-causing environment or lifestyle factors, sometimes it can be inherited. These cancers are caused by an abnormal gene passed along from generation to generation.

Although this is often referred to as inherited cancer, what is inherited is the abnormal gene that can lead to cancer, not the cancer itself. In children with ACT, about 50% test positive for a specific inherited mutation in a gene named TP53. This is why patients with ACT should undergo genetic testing, even if there is no history of cancer in the family.

  1. There are several disorders that are associated with an increase incidence of pediatric ACT.

    ACT is a common cancer among children of families with Li-Fraumeni syndrome (LFS). This is a rare disorder that increases the risk of several different cancers. A similar condition called Li-Fraumeni-like syndrome (LFL) shares many features of LFS. Both conditions greatly increase the chances of developing multiple cancers beginning in childhood. However, the specific tumor types that occur in family members may be different. About 3% to 10% of LFS-associated cancers are ACTs.

    Other disorders that are associated with an increased risk of pediatric ACT include:

  2. There are many things to consider when thinking about TP53 testing. Learning the results of a genetic test can affect your entire family. Before doing genetic testing, think carefully about how knowing the test results might affect you, your child and other family members.  Once a child tests positive for a TP53 mutation, adult family members may want to know if they have the same mutation. Their test results would give them information about their own cancer risk. For this reason, it might be important to tell other family members about the presence of an inherited TP53 mutation.

    If your child’s test does not show the TP53 mutation, your family members will not benefit from testing. You or your child might have sporadic ACT.

    Knowing your family medical history can help you make changes to lower your cancer risk. If you have a higher risk of certain cancers, your doctor might recommend screening tests for other cancers earlier than usual or more often. You or your family members might need other tests and regular checkups by a doctor. Eating healthy foods, getting regular exercise and quitting smoking can lower your chances of getting cancer, heart disease and other conditions.

    Some people choose to have genetic testing because the results can help them decide about cancer screening, treatment and family planning. The presence of an inherited TP53 mutation could make you feel better knowing the reason for developing ACT. This will also help doctors decide about treatment options and help you make decisions about family planning and improving your lifestyle.

    Some families choose not to have genetic testing because they believe knowing about a mutation would make them worry about cancer risk or feel guilty about passing on the mutation. Moreover, some families are just not interested in genetic testing.

    If you aren’t sure about whether to have genetic testing, it can help to talk about it with doctors, genetic counselors and advisers like friends or spiritual leaders. This also applies to children and teenagers. Genetic testing is available at any age and may not be immediately necessary.

  3. How you choose to share test results with family members depends on your comfort level and relationship with each family member. Genetic testing can cause many emotions. Some people might feel better after learning their risk of cancer and other diseases. Other people might worry about their cancer risk or feel they have no control over the future.

    Each person should decide whether to be tested or tell other family members about their test results. Your genetic counselor can help you share the information in the way that is most comfortable for you.

If you have a family history of cancer, or if you would like to find out whether you or a family member has an increased likelihood of developing cancer, we encourage you to consult with a specialist who has experience in the area of hereditary cancer, cancer risk assessment, and genetic counseling and testing.

If you or your child is currently a St. Jude patient, contact the Cancer Predisposition Program