Do your genes put you at heightened risk of developing cancer?
A new at-home test could help you learn more about your genetic risk factors, although it may not be as much assistance as you might think.
Last week, the U.S. Food and Drug Administration (FDA) authorized the company 23andMe to market the first direct-to-consumer test that reports on three specific genetic variants in the BRCA1 and BRCA2 genes.
People with these genetic variants are significantly more likely than average to develop breast, ovarian, and prostate cancer.
“For the variants we will report on, women with the highest risk result have a 45 percent to 85 percent chance of developing breast cancer by age 70, and a 10 percent to 46 percent chance of developing ovarian cancer,” a 23andMe spokesperson told Healthline.
“Men with the highest risk result have an increased chance of developing male breast cancer and prostate cancer,” the spokesperson added.
This test only detects 3 out of more than 1,000 known BRCA mutations.
Similarly, it doesn’t account for many other genetic and nongenetic risk factors for cancer.
In other words, you could receive a negative result on this test and still have a BRCA mutation or other risk factors that increase your chances of developing cancer.
“It’s important to note a negative result — i.e., ‘no variants detected’ — does not significantly reduce one’s cancer risk because other genetic and nongenetic factors not tested here still play a large role in overall risk for these cancers,” the 23andMe spokesperson said.
“However, a positive result is very informative,” they continued, “and may significantly increase one’s genetic risk for certain cancers, especially breast and ovarian cancer.”
A limited group of people
The specific genetic variants detected by the 23andMe test are most common among people of Ashkenazi Jewish descent.
Members of this population are at particularly high risk of carrying BRCA mutations.
“About 1 in 40 people of Ashkenazi Jewish ancestry have a deleterious BRCA mutation, as compared to about 1 in 400 people in the general population,” the 23andMe spokesperson noted.
“The three variants we are testing account for over 90 percent of BRCA-related cancer found in the Ashkenazi Jewish population,” they said.
For members of the population who lack Jewish ancestry, this test may be less useful.
“Essentially what they’re doing is, they’re taking a test for the BRCA gene that’s really applicable to the Jewish population, and they’re marketing it to everyone,” Mary Freivogel, MS, past president of the National Society of Genetic Counselors (NSGC), told Healthline.
“So they are marketing a test that is designed for [a very small portion] of the population to everyone, which means that for [the vast majority] of people who take this test, the BRCA results will mean nothing to them, but they might think that they mean something, so it’s very dangerous,” she added.
Freivogel suggested that more comprehensive genetic testing that detects other types of BRCA mutations is better suited to many patients, including those without Jewish ancestry.
“That’s why genetic counselors are so important in this process because we really need to help patients choose the right test for them depending on their family history, their ethnicity, and all those things,” she said.
In response to Freivogel’s comments, Kathy Hibbs, chief legal and regulatory officer of 23andMe, pointed to the FDA’s authorization of the test as evidence of its viability.
“In gaining authorization, we demonstrated to the FDA that our product was a safe and effective way of providing information on these three BRCA mutations to our customers,” she said.
“Recent data has indicated that genetic counseling is not universally available and requiring it as a gate to accessing the information may exacerbate the number of carriers who are missed by current protocols,” she added, referencing a recent editorial in the Journal of Clinical Oncology.
Hibbs suggested that 23andMe’s new BRCA test “can provide a significant benefit” to people who do carry one of the variants that it detects.
Some of those people might have Jewish ancestry without knowing it.
Addition to existing services
23andMe will incorporate the new BRCA test into its existing Health + Ancestry Service, rather than selling it as a standalone product.
This service provides information about users’ ancestry and genetic risk factors for certain health conditions.
It currently reports on genetic variants related to celiac disease, Parkinson’s disease, late-onset Alzheimer’s disease, and several other conditions.
After purchasing this service, users are asked to mail a sample of their saliva to a laboratory.
When the sample has been tested, their results are made available to them online.
This direct-to-consumer approach to genetic testing allows customers to access information about their genes without the assistance of a genetic counselor or other healthcare provider.
Drawbacks to at-home testing
For some people, direct-to-consumer genetic testing may provide a more accessible alternative to genetic tests ordered by a healthcare professional.
“It’s more accessible, it’s more affordable, and they don’t have to leave the comfort of their own home to get it,” Freivogel said.
On the other hand, people who opt for direct-to-consumer testing might miss out on important information and support that a trained healthcare professional could provide.
Compared to a report from a direct-to-consumer service, a genetic counselor can offer more customized guidance to help people choose the right test and interpret and act on its results.
“Genetics really is only one piece of the puzzle. Even if you have a BRCA mutation, it’s not guaranteed you will get cancer, and obviously if you don’t have a BRCA mutation, you still can get cancer,” Freivogel said.
“So it’s very important how we position the results to patients, whether positive or negative, so patients are acting on them in the way they should to produce the best clinical outcomes that we can,” she added.
A genetic counselor can also help people prepare for the difficult conversations they might face if they test positive for BRCA mutations or other harmful genetic variants.
“Are these consumers ready to share this information with their family? Do they know how to do that?” Freivogel asked. “That’s something they need to think about before they get testing [done].”
Ask your doctor
If you have Jewish ancestry or a family history of breast, ovarian, tubal, or peritoneal cancer, consider asking your healthcare provider if you should be tested for BRCA mutations.
Depending on your family history, your healthcare provider might recommend that you undergo genetic testing or schedule a consultation with a genetic counselor.
If you’re interested in scheduling an in-person or telemedicine appointment with a genetic counselor, you can find one in your area by using the database provided on the NSGC website.