Understanding Genetic Predisposition to Cancer
When a child is diagnosed with cancer, parents commonly ask, “Does this put my other kids at higher risk for developing cancer as well?” Most of the time, the answer to this question is “no”.
However, 5 to 15 percent of childhood cancers are associated with a genetic predisposition to cancer. This means there is a genetic change in the child’s DNA that puts them at increased risk of developing cancer compared to a child without that genetic change.
Families typically seek testing for genetic predisposition to cancer for two reasons. For families already coping with the difficulties of a new cancer diagnosis in their child, the idea that their other children could be at risk of having cancer is a terrifying one. Other families may have experienced cancer in multiple adults and are wondering if it is just bad luck or if cancer really does “run in the family”.
While the majority of cancers are not a sign of a possible genetic predisposition to cancer in the family, there are some diagnoses and patterns that are worth investigating further. Health care providers such as oncologists and genetic counselors can take a detailed family history – called a pedigree – to identify the particular types of cancer that have been diagnosed in one family and the age of development of cancers. From there, they can determine if further genetic testing is needed.
If a child does not have a strong family history of cancer, genetic testing only needs to be done if the child has had more than one type of cancer or has had a cancer known to be related to genetic changes.
Genetic testing is fairly straightforward for some predisposition syndromes, but in many cases, the specific gene or condition to test for might not be obvious. It is important for experts in cancer genetics to take a thorough medical and family history and determine if multiple genes should be tested at once. This is done frequently for patients with concerning personal and family histories using what is commonly called a “gene panel.” A gene panel allows multiple genes to be tested using just one blood or saliva sample.
Prior to genetic testing, thorough counseling is provided to discuss advantages, disadvantages and limitations of testing, as well as to explore the emotional implications for the family. If testing is pursued, results from genetic testing are usually available in about four to six weeks.
Once the results are in, a physician and/or a licensed genetic counselor will go over the results with the family. They will discuss screening and management options, including testing for other family members. Management guidelines vary depending on the specific genetics, age of the individual and cancer history. Because of these complexities, specialists in cancer and genetics are the best resources for developing a personalized management plan.
If you are concerned about you or your child’s risk of cancer, you should discuss your concerns with your primary health care provider. If additional testing or screening is needed, they can refer you to the appropriate cancer genetics program.
At Nationwide Children’s Hospital, cancer genetic counseling services can be reached by calling 614-722-3695.
Contributing Author: Elizabeth Varga, MS, LGC is a licensed genetic counselor in the Division of Hematology/Oncology/ Bone Marrow Transplant. Ms. Varga has 12 years of experience as a genetic counselor and has specialized in pediatric Hematology/Oncology for the past 5 years. She currently provides clinical genetic counseling and participates in research related to genetics of blood and cancer.