Genetic Testing for Hereditary Colorectal Cancer
About 3% of colorectal cancer cases are due to an inherited condition known as Lynch syndrome (sometimes referred to as hereditary nonpolyposis colorectal cancer or HNPCC). People with this condition have a greatly increased chance of developing colorectal cancer, especially at a young age (younger than 50 years). Parents, children, sisters, and brothers of people with Lynch syndrome have a 50% chance of having this condition. Other blood relatives such as grandparents, aunts, uncles, nieces and nephews are also at increased risk to have Lynch syndrome.
Genetic Testing for Lynch Syndrome
Genetic testing is used to find out if a person's colorectal cancer is hereditary (caused by an inherited gene change), so that family members can learn if they are also at increased risk. This could help to protect them from getting this disease. Several different genetic testing strategies are available for Lynch syndrome, including screening of tumor tissue samples and/or diagnostic testing of DNA from non-cancerous tissue samples.
The Evaluation of Genomics in Practice and Prevention (EGAPP™) Working Group found good scientific evidence to show that if individuals with colorectal cancer are found through genetic testing to have Lynch syndrome, their family members can benefit:
- by undergoing genetic testing to learn if they are also at increased genetic risk.
- by having earlier and more frequent screening, which can prevent colorectal cancer, if the person is at increased genetic risk.
However, there was insufficient evidence to specify which genetic testing strategy would work best.
The EGAPP Working Group concluded that all people with a new diagnosis of colorectal cancer should be offered counseling and educational materials about genetic testing for Lynch syndrome. Learn more.
Listen to a podcast about genetic testing for Lynch syndrome.
Although the EGAPP recommendation did not address use of testing in other situations, people with colorectal cancer diagnosed in the past (especially under age 50), and/or people with several family members with colorectal and/or uterine cancer may also benefit from genetic evaluation for Lynch syndrome.
In addition to talking with your health care provider, the Web sites below provide more information on colorectal cancer, Lynch syndrome, cancer genetic testing, and access to genetic counseling services.
- Colorectal Cancer, Centers for Disease Control and Prevention
- Lynch Syndrome, Genetics Home Reference, U.S. National Library ofMedicine
- Understanding Cancer Series: Gene Testing, National Cancer Institute
- Cancer Genetic Services Directory, National Cancer Institute
- Find-A-Counselor, National Society of Genetic Counselors
The EGAPP™ Working Group is an independent panel of scientists and health care experts from universities, industry, clinical practice, insurance companies, and public health who review available research and evidence to make recommendations about the use of genetic tests.
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