You’ve Heard About Genetic Testing. Is It for You?
A Dana-Farber geneticist answers your questions about genetic testing for cancer.
Jolie, who lost her mother, grandmother, and aunt to cancer, tested positive for BRCA1, a gene that heavily predisposes women to both breast and ovarian cancer. With her breast cancer risk estimated at 87 percent, Jolie opted to have both of her breasts removed proactively. She later had her ovaries and fallopian tubes removed as well.
Since the actress had her first surgery in 2013, the world of genetic testing has evolved. Science has advanced. Laws have changed. Costs have come down. Where does that leave us today? We asked Huma Rana, clinical director of cancer genetics and prevention at Dana-Farber Cancer Institute, for answers.
Who should get tested?
Rana says there are five main groups who should be tested for a genetic risk of cancer:
- Women with a strong family history of breast and/or ovarian cancers.
- Anyone—man or woman—who has a family member with a genetic mutation, such as BRCA1 or 2. Men with family histories of these mutations may be at higher risk of prostate cancer.
- Any woman who has had an ovarian cancer diagnosis.
- Any woman who had a breast cancer diagnosis younger than age 50.
- Anyone with a strong family history of colon cancer or colon polyps.
“Those are the people who should absolutely come in for testing,” Rana says. “There have been so many improvements in technology that have enabled us to test more genes, or numerous genes in parallel, and to do it extremely cost-effectively.”
Rana recommends testing beginning around age 25 for women and age 35 for men, or when you’re thinking of having children.
What if I’m just worried?
Without a family or personal history, it’s probably unnecessary to subject yourself to extra testing. “These are rare conditions and rare genetic susceptibilities, for the most part,” Rana says. “You’re always going to have more people who are worried about them than people who have them.”
What will it cost?
Prior to 2013, looking at just two genes cost $4,000. Advances in science, technology, and law, however, have significantly reduced costs, and many insurance providers now cover testing for those with risk, Rana notes.
How does the test work?
The easiest way to explain it, Rana says, is to think about genes like a recipe. “Each gene is a recipe to make a protein,” she says. “The proteins that we test for are proteins that are components of our DNA repair machinery, so they help to keep your cells growing and dividing normally, and not taking off and proliferating in ways that they shouldn’t.”
When your blood or saliva is submitted for genetic testing, scientists look for alterations in the “recipe”—variations that could affect the end result.
If the recipe is intact, you likely don’t have genes that bump your cancer risk. If there are alterations, they either signify that proteins are not being made correctly, which puts you at higher risk of disease, or that they’re of uncertain significance. “More often than not, it’s just part of normal human variation,” Rana explains. “It’s sort of like how you can spell theater two ways.”
Testing seems like it’s for me. What now?
See a genetic counselor and discuss your options. And don’t panic—Rana stresses that many people, even those with a clear family history, end up testing negative, which can be an enormous relief. “People are fearful of having the testing, but also they’re living with the fear of developing these cancers,” Rana says.
Even those who test positive may not need to make the life-altering decisions that Jolie did. Not every gene is correlated with a significant cancer risk, and next steps will vary from person to person. A positive result may simply mean you should get screened more often.
“We’ve seen how valuable this information is for patients,” Rana says. “It really is empowering to have this type of information.”