Scientists have made incredible progress in learning to read and understand our genes in the last 20 years – and their link to certain cancers.
Genes, which are the building blocks that make us who we are, get passed down to us by our parents. In each generation, some of those building blocks carry changes, known as mutations.
Cancer researchers, like those at City of Hope, have come to understand that mutations in certain genes can mean a higher likelihood of getting certain types of cancer. That’s why genetic testing to identify these mutations has become an important tool in figuring out people’s risk of getting cancer in their lifetimes.
But genetic testing is complicated, and most patients don’t entirely understand what it is for, or why they should consider it.
“It’s a test to look at the genetic code of certain genes for mutations that may be inherited in your family,” said Ilana Solomon, Sc.M., a genetic counselor at City of Hope.
These tests look for mutations that increase your risk for certain types of cancer, most commonly breast, ovarian and colon cancer, she said. The most well-known examples of mutations are in the BRCA1 and BRCA2 genes, which are associated with hereditary breast and ovarian cancer. Getting tested can offer information about your own cancer risk, and also help provide a more complete picture for your family members.
“If you have a family member with cancer, especially two or more people in your immediate family, consider talking with a board certified genetic counselor or geneticist,” said Thomas Slavin, M.D., an assistant clinical professor in the Department of Medical Oncology & Therapeutics Research at City of Hope.
2. How is a genetic test different from regular cancer screening tests?
Screenings such as a mammogram, MRI or colonoscopy are used to find existing cancer in the body. Genetic tests are a tool that doctors can use to help figure out how likely you are to get certain cancers in the future.
A positive result on a genetic test may lead your doctor to recommend more frequent screening tests. Genetic tests can also be useful for patients who already have cancer, by helping to guide treatment based on mutation-related cancer risks.
3. How do I know if I should get a genetic test?
“Usually patients are either referred to us by their doctor, or they come self-referred because of their family history of cancer,” said Solomon. As a genetic counselor, she helps patients decide if genetic testing is right for them.
“We start with a questionnaire before they even come in,” she said. “Then, they meet with a genetic counselor who reviews their personal and family history. Every person should have pre-test counseling before they get tested so they understand the implications of the genetic test and how the test should be interpreted.”
4. Does a positive result for a known hereditary cancer mutation mean I have cancer?
No. And the opposite is also true.
“One of the biggest issues with these tests is that people think of the test result as a definitive answer,” Slavin said. “Just because you have a positive result doesn’t mean you have cancer, it just helps us understand the risk. And a negative result doesn’t mean you won’t get cancer. There could be other factors in your life that influence your risk.”
It’s important to realize that only 5 to 10 percent of all cancers are hereditary, with most cases resulting from a variety of other reasons. Cigarette smoking is one example of a nonhereditary risk factor.
5. Is the procedure complicated? Is it uncomfortable or painful?
The appointment is quick and easy.
“The test itself is typically a blood draw,” Solomon said. “It’s really simple, and you don’t even have to fast beforehand like you do with some other blood tests.”
After the initial appointment, it usually takes a few weeks or more to receive the results. At that point, it’s very important that the results are interpreted by a genetics professional, such as the ones at City of Hope.
6. How much does genetic testing cost? Is it covered by insurance?
Depending on the type of genetic testing, the cost can range from a few hundred dollars to a few thousand. In most cases, the tests are covered by a patient’s health insurance.
“As long as the patient meets established guidelines for needing the test, it is usually covered by insurance,” Solomon said.
“A big part of our role as genetic counselors is acting as patient advocates, and that includes dealing with insurers to make the case for why it is medically necessary and should be covered.”
7. Will a positive result cause me to lose my insurance, or my premiums to go up?
A positive result won’t have any effect on your health insurance premiums thanks to the Genetic Information Nondiscrimination Act of 2008. This is a federal law passed to protect people from genetic discrimination in both health insurance and at their jobs. It also means that you can’t be fired for a positive result.
8. Does my ethnic background influence my genetic predisposition to cancer?
For most people, the answer is no. The only ethnic background known to have a higher carrier frequency at this time is the Ashkenazi Jewish population, who have a higher likelihood of carrying certain BRCA1 and BRCA2 mutations. Ashkenazi Jews are those originating from central and eastern Europe, as opposed to Sephardic Jews, who originate in the Middle East and North Africa.
The National Institutes of Health funding will support a City of Hope study of a rare cancer-causing syndrome linked to an inherited mutation in the TP53 gene. Li-Fraumeni syndrome causes various cancers early in life.