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About three to five percent of colorectal cancers are believed to be caused by mutations in the MLH1, MSH2, MSH6 , PMS2 or EPCAM genes.1 When a patient carries a mutation in any of these genes, he/she has a condition called Lynch syndrome also known as Hereditary Non-polyposis Colorectal Cancer (HNPCC) syndrome.
People with Lynch syndrome are also at higher risk of developing several other types of cancer, including:
Some patients with Lynch syndrome may also develop sebaceous adenomas, noncancerous tumors of the sebaceous glands.
Myriad offers genetic testing to determine whether your patient is a carrier of any of the genetic mutations associated with Lynch syndrome.
If a patient’s personal or family history indicates that he/she may be at an increased risk for Lynch syndrome, genetic test results provide the most accurate way to assess that patient’s cancer risk. Knowing the risk can help you and your patient make better and more informed decisions before the onset of cancer or before a second cancer has had a chance to develop.
Genetic testing for hereditary colon cancer should be considered if:*
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Approximately two percent of all colon cancer is thought to be caused by one of three adenomatous polyposis conditions:2,3
Classic familial adenomatous polyposis (FAP) and attenuated familial adenomatous polyposis (AFAP) are due to mutations in the adenomatous polyposis coli (APC) gene. Approximately 20 percent of APC-associated polyposis syndromes are caused by de novo mutations, in which an APC mutation is present in an individual, even though it is absent in both parents.4
MYH-associated polyposis (MAP) is caused by mutations in the mutY homolog (MYH) gene. This gene is an important part of the base excision repair (BER) pathway, which allows for repair of DNA mutations caused by oxidative damage to cells. Individuals with MAP have biallelic MYH mutations, or mutations in both of the MYH genes inherited from each parent. They often have no family history of colon cancer or polyps in their parents (although siblings may be affected).5
Since some polyposis syndromes like AFAP or MAP may not present with a significant personal/family history of colon cancer or colon polyps, genetic testing may be a useful tool to identify at risk individuals.4,5 Myriad offers genetic testing to determine whether your patient is a carrier of any of the genetic mutations associated with Lynch syndrome.
Identifying people who are at risk for adenomatous polyposis syndromes and monitoring them is perhaps the most critical step in changing hereditary cancer outcomes. Genetic testing for a polyposis syndrome should be considered for:*
You can use the Myriad Hereditary Cancer Quiz as a tool to help you identify patients who may benefit from hereditary cancer testing.
If hereditary cancer testing confirms the presence of a MLH1, MSH2, MSH6 or PMS2 mutation, the following medical management options may help reduce colon cancer risk and may either delay the onset of cancer or detect it at an earlier, more treatable stage: †
If hereditary cancer testing confirms the presence of an APC or MYH mutation, the following medical management options may help reduce cancer risk and may either delay the onset of cancer or detect it at an earlier, more treatable stage:6
*Assessment criteria are based on individual medical society guidelines.
**Lynch-associated cancers include colon, endometrial, gastric, ovarian, urinary tract, renal/pelvic, biliary tract, small bowel, pancreatic, brain and sebaceous adenomas.
†Any discussion of medical management options is for general informational purposes only and does not constitute a recommendation. While genetic testing and medical society guidelines provide important and useful information, all medical management decisions should be made based on consultation between each patient and his or her healthcare professional.