Risk Factors for 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 several close relatives have a history of colon cancer, the risk is even greater.
Changes in certain genes increase the risk of colon cancer. Examples include:
- Hereditary nonpolyposis colon cancer (HNPCC). This 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 develop colon cancer; the average age at diagnosis is 44.
- 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 people who have changes in their genes, healthcare providers may suggest ways to try to reduce the risk of colon cancer or to 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.
Personal History of Colon Cancer
A person who has already had colon cancer may develop it a second time. Also, women with a history of cancer of the ovary, uterus, or breast are at a somewhat higher risk of developing colon cancer.