The social media influencer Alix Earle, who is 25, revealed in a documentary released Friday that she and her sister tested positive for an inherited mutation in a BRCA gene.
People with mutations in the BRCA 1 or 2 genes have more than a 50 percent chance of developing breast cancer in their lifetime, compared with roughly 13 percent in the general population, said Dr. Kala Visvanathan, an oncologist and director of the Clinical Cancer Genetics and Prevention Service at Johns Hopkins University. They are also more likely to develop breast cancer before age 50.
But, doctors don’t recommend that everyone receive genetic testing for inherited cancer mutations. Here’s what to know.
Who should get genetic testing for breast cancer risk?
The National Comprehensive Cancer Network, an alliance of leading cancer centers, issues guidelines for who should receive genetic testing. These tests look for inherited mutations, so this includes people with close blood relatives like grandparents, parents or siblings who had breast cancer before age 50 or who had male breast cancer or triple-negative breast cancer at any age.
“Knowing your family history is an important first step to take,” said Dr. Mary Daly, director of the risk assessment program at Fox Chase Cancer Center in Philadelphia and chair of the guidelines committee. That includes the history on both your mother and your father’s side, and not just for breast cancer. Dr. Visvanathan said that “there are other cancers that can be in the family that would suggest a hereditary predisposition,” including ovarian, pancreatic and prostate cancers. (Melanoma may also be linked, though there is some debate in the field, Dr. Daly said.)
Doctors recommend that eligible people consider testing starting in their 20s to identify genetic risk before cancer might develop. Insurers will typically cover the test for people who meet the criteria. Costs vary, but can be around $250 out of pocket.
Genetic testing may also be recommended for people who have been diagnosed with breast cancer, as the results could inform treatment and have important implications for family members. Ms. Earle and her sister decided to get tested after their mother was diagnosed with breast cancer and tested positive for a BRCA gene.
Experts don’t recommend testing in the broader population because the tests aren’t as likely to have a benefit, they can be costly, and the health system may not have enough resources to provide follow-up care to everyone.
How do you get the test?
If you’re interested, talk to your doctor about a referral for genetic counseling, said Dr. Tuya Pal, a clinical cancer geneticist at Vanderbilt University Medical Center and vice chair of the guidelines committee.
If your provider says no, “have them explain to you why,” Dr. Pal said, adding that providers should be able to state why someone wouldn’t be considered high-risk. You can also search on the National Society of Genetic Counselors website, or go to a cancer genetics and prevention clinic at a cancer center.
If you and a counselor agree testing makes sense, you would provide a blood or saliva sample that could be tested for several genes at once. These include about a dozen genes with mutations related to breast and associated cancers. You could also be tested for a broader set of mutations, including those that predispose people to colon, endometrial and gastric cancers, though that can have drawbacks for patients.
“We may uncover a cancer risk that they were not thinking about,” said Dr. Veda Giri, director of the cancer genetics and prevention program at Yale, who noted that can cause anxiety and lead to additional screening and preventive measures.
What will the results tell you?
If a test comes back positive, that means it identified a “pathogenic,” or cancer-causing, variant in one or more of the genes. That doesn’t necessarily mean you will develop cancer, however, nor does a negative result mean that you will never develop cancer. About five to 10 percent of all breast cancers are related to hereditary genes. Among women under 50, the proportion is closer to 25 percent, Dr. Visvanathan said.
Sometimes the test can identify “variants of uncertain significance,” a kind of gray zone in which a change to the gene isn’t known to be pathogenic but isn’t known to be benign, either. These can occur in up to a third of patients who receive comprehensive cancer gene panels, Dr. Giri said.
Many of the variants end up being reclassified, most commonly as benign, Dr. Daly said, and they don’t change the medical recommendations that doctors make.
How will a positive result change your care?
If a patient tests positive for a gene that increases breast cancer risk, “the first thing we try and do is develop a clinical plan for monitoring their breast health,” Dr. Daly said. That could include being seen in a high-risk breast screening clinic and having earlier and more frequent screening, with both mammograms and M.R.I.s.
M.R.I.s are more sensitive than mammograms, Dr. Visvanathan said, and can be particularly helpful when someone has dense breasts.
With patients who have a BRCA gene mutation, doctors may discuss preventive surgeries, including mastectomy and salpingo-oophorectomy, removal of the ovaries and fallopian tubes. These “are very, very personal” decisions, Dr. Visvanathan said.
Patients with these mutations may have more nuanced discussions with their doctor about hormonal birth control, or hormone replacement therapy after menopause, Dr. Daly said. Doctors may also prescribe tamoxifen, a chemotherapy drug that also reduces breast cancer risk, to eligible patients.
Men who have a positive BRCA result may be recommended for prostate cancer screening with a P.S.A. test and an M.R.I. Men and women who test positive may be counseled to get pancreatic cancer screening. Though researchers are still figuring out the best way to do that — including M.R.I., ultrasound and blood-based biomarkers — there are options available through clinical studies, Dr. Daly said.
In the documentary, Ms. Earle doesn’t linger on the test result too long. “At least we know, and that’s such a privilege,” she tells her sister.
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