There is no single cause of colon cancer. Yet, nearly all colon cancers begin as noncancerous (benign) polyps, which slowly develop into cancer. In most cases, colon cancer begins in glands in the lining of the colon and rectum.
Those at a higher risk for colon cancer include individuals who:
- Are older than 60 years of age
- Are African American of eastern European descent
- Eat a diet high in red or processed meats
- Have cancer elsewhere in the body
- Have colorectal polyps
- Have inflammatory bowel disease (Crohn's disease or ulcerative colitis)
- Have a family history of colon cancer
- Have a personal history of breast cancer
Certain genetic syndromes also increase the risk of developing colon cancer. Two of the most common are:
Familial adenomatous polyposis (FAP) – an inherited condition in which numerous polyps form mainly in the large intestine.
Hereditary nonpolyposis colorectal cancer (HNPCC), also known as Lynch syndrome (a dominant genetic condition which has a high risk of colon cancer, as well as other cancers.