Genetic Testing and Hereditary Cancer: What You Need to Know
What is genetic testing for hereditary cancer?
About 10-15% of people with cancer have an inherited predisposition for certain kinds of cancer. (This increases to about 20-25% of people with either ovarian or metastatic prostate cancer.) A hereditary cancer predisposition means that a mutation (broken copy) in a gene is inherited from either parent, which leads to higher cancer risks over their lifetime. Mutations in some genes can cause an increased risk for breast, prostate, ovarian, and pancreatic cancer. When other genes are broken from birth, this increases the risk for colon, endometrial, and other cancers. Genetic testing can help discover if someone has a hereditary cancer predisposition.
What are the benefits of genetic testing?
Patients sometimes ask why they should have genetic testing if they already know they have cancer. While this is true, genetic testing can help us know if the patient or their family members may be at an increased risk for other cancers in the future. If so, there often are changes to medical management, such as increased screenings or preventative surgeries in some cases, that may be recommended.
Genetic testing can also help clarify if there may be a risk for other family members to have inherited a cancer predisposition. Testing the person with cancer is generally considered more informative than testing their children who haven’t had cancer. This is because if the child doesn’t have a mutation found on their genetic testing, their parent may still have had a mutation that just wasn’t passed on to them, but could have been passed on to their other children. However, what if a parent with cancer has negative (normal) genetic testing first? In that case, their children generally don’t need genetic testing, unless there is a concern from their other parent’s side of the family.
In addition, genetic testing can sometimes change the treatment of the patient’s current cancer. For example, some genes are prognostic of a prostate cancer being more likely to become aggressive. In these cases, a provider may recommend definitive treatment (surgery or radiation) when they otherwise may have offered active surveillance. Genetic testing can also indicate that specific targeted therapies may be more useful for a particular patient.
Benefits of meeting with a genetic counselor before and after genetic testing
Genetic counselors are healthcare providers with graduate training in genetics and how to communicate complex medical information to patients. A genetic counselor will usually meet with a patient before testing to review their personal and family history of cancer. They can then determine if genetic testing is recommended and explain possible genetic findings. By documenting the history of cancer in the family, they can improve the likelihood of insurance covering genetic testing, when appropriate. A genetic counselor will explain the benefits and risks of genetic testing for the patient to help them make an informed decision.
After genetic testing results are available, a genetic counselor can explain any findings and medical management recommendations. They can also identify other family members who may benefit from genetic testing. For patients who have a mutation identified, we often provide patients with a letter they can give to their family members explaining their results and why genetic testing is recommended for the family member.
Cancer takes a terrible toll. But when we can proactively identify people who are at higher risk due to an inherited mutation in a cancer predisposition gene, we can target appropriate medical management to prevent cancer or catch it at an earlier, easier-to-treat stage. Hereditary cancer genetic testing is one way we can thwart cancer and improve outcomes for future generations.
First published on cscatlanta.org
