Published Jan 28, 2019

23andMe’s New Colon Cancer Test — It Does Not Assess all of Your Risk. Buyer Beware!

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There is a new test for colon cancer from a company called 23andMe. A lot of people have heard of the company because it’s one of the leaders in a field that’s exploding — direct-to-consumer genetic testing. The new test looks for a fairly rare gene that could put you at risk for colon cancer. What a lot of people may not realize is that a lot of other genes carry risk for colon cancer, so if you take this test, you still may have risk.

According to Wendy Kohlmann, Genetic Counselor at the Huntsman Cancer Institute at the University of Utah, “The test that they are offering looks for a very specific genetic condition associated with a high risk of colon cancer. The specific gene they are looking for is called MUTYH. People have two copies of each gene, and if you have a mutation on both copies of this gene, it is associated with polyps in the colon and a high risk of cancer,” says Kohlmann.

“However,” Kohlmann explains, “this is exceedingly rare. If someone does have two mutations in the MUTYH gene it could save their life, however that is very very rare, and this is certainly not something that is going to be significant for most people for determining their colon cancer risk.”

“The other concern is that while it’s rare for people two have two mutations, it is very common for people to have one. There is a lot of conversation right now in the medical community about whether having one is very important. Some have speculated that having one mutation is important,” she says. “There are groups such as the national comprehensive cancer network, which at this point in time does not recommend any specific screening or anything different for people who have one MUTYH mutation. If you have one mutation and a history of colon cancer then you might want screening at a younger age, but then we would have recommended that anyway if you have a family history of colon cancer.”

Anne Wojcicki, 23andMe CEO and co-founder, is quoted in the product announcement, "We are committed to giving people affordable and direct access to important health information that can impact their lives." According to Kohlmann, there may be other low cost options to know about, “There are lots of options for genetic testing, there are laboratories that offer more extensive testing of genes that is often covered by insurance if there is a family history of colon cancer. 23andMe is a low cost option, and they offer a lot of services that aren’t part of genetic testing. But for people who are worried about colon cancer because they’ve had it in the family, there should low cost options available.”

“If things like 23andMe are getting people to think about their health and their family history then that’s a great thing,” she says, “so it’s not like we have any particular issue with 23andMe, it’s just that we want people to know that this is really a snapshot of the information that is available.”

According to Rachel Webster, Genetic Counselor at MD Anderson Cancer Center, “Direct-to-consumer genetic testing can be a very useful tool for some individuals. That said, having someone take a look at your history and your family history is a very useful tool in figuring out if a direct-to-consumer test would identify the risk in your family. There is no such thing as a one-size-fits-all test as much as direct-to-consumer testing options have tried to build those.”

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