Genetic Factors and Colorectal Cancer: Know Your Risk
by C.H. Weaver M.D.
Because these known factors can be identified through genetic testing, it’s important to understand your risks and to discuss them with your healthcare provider.
The following are three hereditary factors that can increase your risk for colorectal cancer:
- People with a personal or family history of adenomatous polyps or familial adenomatous polyposis (FAP) are at an increased risk for developing colorectal cancer. Adenomatous polyps are non-cancerous tumors that grow in the colon or rectum and become cancerous, ultimately developing into colorectal cancer. FAP is a genetic disease that causes hundreds of adenomatous polyps to form in the colon or rectum. FAP most often affects adolescents and young adults, many of whom develop colorectal cancer at an early age.
- Hereditary nonpolyposis colorectal cancer (HNPCC) is a genetic syndrome caused by mutation in one of several genes. HNPCC accounts for about 3–5% of all colorectal cancer. With HNPCC, people develop a single colorectal cancer rather than an unusual number of polyps as in FAP. Individuals with the HNPCC gene mutations have an 80% lifetime risk of developing colorectal cancer.
- Individuals with a family history of colorectal cancer or colorectal adenomas (polyps) also have an increased risk of developing colorectal cancer, as do those with a personal history of either of these conditions. (In addition, people suffering from inflammatory bowel disease have a greater chance of developing colorectal cancer.) Research indicates that the presence of a gene called the pituitary tumor transforming gene (PTTG) may help to identify colon polyps most at risk for becoming cancerous.
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The good news for people who do have a hereditary risk for colorectal cancer is that prevention methods exist to help reduce risk of developing the disease, as do effective screening measures that can diagnose colorectal cancer in its early, most treatable stages. If you have any of these risk factors, consult your physician about ways to help reduce your risk and about setting up an appropriate screening schedule. Your healthcare provider can also help you assess your family and personal medical history to determine if you’re a candidate for genetic testing for colorectal cancer risk.