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Hereditary Cancer and Genetic Testing

Cancer risks in people with inherited MUTYH mutations

MUTYH-associated polyposis (MAP)

People with MAP tend to develop multiple polyps in their colon; although the number can range  from 20 to over 100 depending on the individual. MAP is associated with a very high lifetime risk for colorectal cancer, although the exact risk is unknown. It may also increase the risk for cancers of the upper gastrointestinal tract, including cancer of the stomach or small intestine. Some research has also linked MAP to an increased risk for thyroid cancer. The exact risks for these cancers are unknown.

It is important to note that the colorectal cancer risk in MAP may happen before the development of a large number of polyps. One study showed that nearly half of MAP patients with colorectal cancer had 10 or fewer lifetime polyps by the time they developed colorectal cancer. For this reason it's important for people with MAP to follow recommended screening guidelines, even if they have not had a large polyp burden.

These risks do not apply to people who have a mutation in only 1 copy of their MUTYH gene. See below for the specific cancer risk information for people with a single MUTYH mutation. 

   

Risks for people with a single MUTYH mutation

People with one MUTYH mutation do not develop MAP. Unlike people with MAP, people with a single mutation may only a slightly elevated risk for colorectal cancer above the general population, and only if they have a relative who had colorectal cancer.

Last updated February 13, 2022