Lynch syndrome is the most common cause of hereditary colon cancer. Myriad myRisk™ Hereditary Cancer uses next-generation sequencing technology to identify patients who may be at risk so that they can take steps to lower their risk of cancer.
About three to five percent of colon or rectal cancers (colorectal cancers) are believed to be caused by mutations in the MLH1, MSH2, MSH6 or PMS2 genes.1 When someone carries a mutation in any of these genes, they have a condition called Lynch syndrome, which is also called Hereditary Non-polyposis Colorectal Cancer (HNPCC) syndrome.
People with Lynch syndrome are at higher risk of developing several different types of cancer, including:
- Colorectal cancer
- Uterine (endometrial) cancer
- Ovarian cancer
- Stomach cancer
- In addition, rarely, urinary/renal, pelvic, biliary tract, small bowel, pancreatic, and brain cancers
Some people with Lynch syndrome may also develop sebaceous adenomas, which are noncancerous tumors of an oil-producing gland in the skin.
Assessing Your Risk for Lynch Syndrome
Myriad offers genetic testing to determine whether you are a carrier of any of the gene mutations associated with Lynch syndrome. In order to assess your risk of carrying these mutations, your healthcare professional may ask you questions about your personal and family medical history. If you are identified as being at increased risk for Lynch syndrome, genetic testing provides the most accurate means of determining your risk of developing cancer.
To help you assess whether you may be benefit from hereditary cancer genetic testing, take the Myriad Hereditary Cancer Quiz. This quiz can help you get the information you need to discuss your risk of cancer with your healthcare professional and ask for further evaluation.
Risk Factors for Lynch Syndrome
Knowing your risk for Lynch syndrome can help you and your healthcare professional make better, more informed decisions about your health, before the onset of cancer or before a second cancer has had a chance to develop. Genetic testing for hereditary colon cancer with the Myriad myRisk™ Hereditary Cancer test should be considered if:*
- Have had colorectal or uterine cancer before age 50
- Have had an abnormal MSI/IHC tumor test result (colorectal/uterine)
- Have had two or more Lynch syndrome cancers** at any age
- Have had a Lynch syndrome cancer and one or more of your relatives has also had a Lynch syndrome cancer**
- Have a previously identified Lynch syndrome mutation in the family
- Has had two or more family members with a Lynch syndrome cancer,** one before the age of 50
- Has had three or more family members with a Lynch syndrome cancer** at any age
- Has a previously identified Lynch syndrome mutation in the family
- Familial adenomatous polyposis
- Attenuated familial adenomatous polyposis
- MYH-associated polyposis
Classic familial adenomatous polyposis (FAP) and attenuated familial adenomatous polyposis (AFAP) are due to mutations in the adenomatous polyposis coli (APC ) gene. It is important to note that approximately 20 to 30 percent of FAP cases are caused by new mutations, meaning that an APC mutation may be present in an individual, even if it is absent in both parents.4
MYH-associated polyposis (MAP) is caused by mutations in the mutY homolog (MYH ) gene, which plays an important role in DNA repair. Individuals with MAP have mutations in both of their MYH genes, one from each parent, and they often have no family history of colon cancer or polyps in their parents (although siblings may be affected).5
Assessing Your Risk for a Polyposis Syndrome
Myriad offers genetic testing to determine whether you are a carrier of a gene mutation associated with a polyposis syndrome. In order to assess your risk of carrying one of these mutations, your healthcare professional may ask you questions about your personal and family medical history. If you are identified as being at increased risk for a polyposis syndrome, genetic testing provides the most accurate way to determine your risk of developing cancer.
To help you assess whether you may benefit from hereditary cancer genetic testing, take the Myriad Hereditary Cancer Quiz. This quiz can help you get the information you need to discuss your risk of cancer with your healthcare professional and ask for further evaluation.
Risk Factors for a Polyposis 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. In order to assess your risk of carrying a mutation in the APC or MYH genes, your healthcare professional may ask you questions about your personal and family medical history. Genetic testing for a polyposis syndrome should be considered if:
- You have multiple colorectal adenomas (usually 10 or more cumulative adenomas)
- You are a relative of an APC or MYH mutation carrier
Using Hereditary Cancer Testing to Reduce Your Colon Cancer Risk
In Lynch Syndrome
If the Myriad myRisk™ Hereditary Cancer test confirms the presence of a MLH1, MSH2, MSH or PMS2 mutation, the following medical management options may help reduce cancer risk and may either delay the onset of cancer or detect cancer at an earlier, more treatable stage:†
- Increased surveillance for colon, uterine and ovarian cancer, such as starting cancer screening at an earlier age or being screened more frequently
- Surgical management
- Chemoprevention (risk-reducing medications)
In Polyposis Syndromes
If the Myriad myRisk™ Hereditary Cancer test confirms the presence of an APC or MYH gene mutation, your healthcare professional may choose among the following medical management options to help reduce cancer risk and either delay the onset of cancer or detect it at an earlier, more treatable stage:
- Counseling for mutation carriers and their family members on the underlying cause of the cancer or adenomas.
- Increased surveillance and other interventions specifically intended for individuals with the APC or MYH gene mutations.
- Improved compliance with tailored screening recommendations and preventive measures.
- Significantly improved colon cancer survival rates and reduced medical costs through early diagnosis and treatment of cancer, should it develop.
*Assessment criteria are based on medical society guidelines.
**Lynch syndrome-associated cancers include colon, uterine/endometrial, gastric, ovarian, ureter/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.
1. Giardello RM, Brensinger JD, Petersen GM. AGA technical review on hereditary colorectal cancer and genetic testing. Gastroenterology 2001;121:198-213.
2. Burt R, Neklason DW. Genetic testing for inherited colon cancer. Gastroenterology 2005 May;128(6):1696-716.
3. Halford SE, et al. Germline mutations but not somatic changes at the MYH locus contribute to the pathogenesis of unselected colorectal cancers. Am J Pathol 2003;162(5):1545-8.
4. Bulow S, et al. The incidence rate of familial adenomatous polyposis: results from the Danish Polyposis Register. Int J Colorectal Dis. 1996;11:88-91.
5. Al-Tassan N, et al. Inherited variants of MYH associated with somatic G:C-->T:A mutations in colorectal tumors. Nature Genetics 2002;30:227-32.