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Genetic Basis for Colorectal Cancer Found

Some Patients Have Changes on a Specific Gene
WebMD Health News

Nov. 2, 2004 -- Mutations on a certain gene may raise the risk of colorectal cancer, which could partially explain why the disease runs in some families, according to a new study.

Colorectal cancer is the third most common kind of cancer and the second most common cause of cancer-related deaths in North America, say the researchers, including Steven Gallinger, MD, MSc, FRCS, of Canada's Mount Sinai Hospital in Toronto.

Because up to 20% of colorectal cancer patients have a family history of the disease, Gallinger and colleagues looked for a genetic basis to that pattern. Specifically, they focused on two mutations on a gene called the MutY human homologue (MYH).

The researchers recruited more than 2,400 participants, half of whom had colorectal cancer. Participants were screened for the two MYH mutations.

Carriers of either mutation had twice the risk of colorectal cancer as those with no such mutations, the researchers write in the Nov. 3 issue of the Journal of the National Cancer Institute.

Patients with either or both mutations had a mean age at diagnosis that was significantly younger than those without the gene mutations. They were also more likely to have a first-degree relative (parent or sibling) or a second-degree relative (such as a grandparent, aunt, or uncle) with colorectal cancer.

Not all colorectal cancer patients have either or both mutations. In addition, the mutations don't automatically mean that someone will develop colorectal cancer.

The researchers call for larger studies on the topic. Meanwhile, they say the risk associated with the mutations should be considered in genetic testing and could also help in colonoscopy screening recommendations for high-risk people.

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