Colon Polyps
Polyps are growths on the inner wall of the
colon or rectum. They are common in people over age 50. Most polyps are benign (noncancerous), but some polyps (adenomas) can turn into cancer. Finding and removing polyps may reduce the risk of
colon cancer.
Family History of Colon Cancer
Close relatives (parents, brothers, sisters, or children) of a person with a history of colon cancer are somewhat more likely to develop this disease themselves -- especially if the relative had the cancer at a young age. If many close relatives have a history of colon cancer, the risk is even greater.
Genetic Alterations
Changes in certain genes increase the risk of colon cancer. For example, hereditary nonpolyposis colon cancer (HNPCC) is the most common type of inherited (genetic) colon cancer. It accounts for about 2 percent of all cases of colon cancer. It is caused by changes in an HNPCC gene. About 3 out of 4 people with an altered HNPCC gene will develop colon cancer, and the average age at diagnosis is 44.
Another type of genetic colon cancer is familial adenomatous polyposis (FAP). This is a rare, inherited condition in which hundreds of polyps form in the colon and rectum. It is caused by a change in a specific gene called APC. Unless familial adenomatous polyposis is treated, it usually leads to colon cancer by age 40. FAP accounts for less than 1 percent of all colon cancer cases.
Family members of people who have HNPCC or FAP can have genetic testing done to check for specific genetic changes. For those who have changes in their genes, healthcare providers may suggest ways to try to reduce the risk of colon cancer or improve the detection of this disease. For adults with FAP, the doctor may recommend an operation to remove all or part of the colon and rectum.
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