Risk Factors for Colon Cancer
Examples of colon cancer risk factors include being 50 years of age or older, having colon polyps, smoking, having a personal or family history of colon cancer, and eating a high-fat, low-fiber diet. Risk factors do not cause the disease itself; however, people with one or more risk factors are more likely than others to develop the cancer.
No one knows the exact causes of colon cancer. Doctors can seldom explain why one person develops the disease and another does not. However, it is clear that colon cancer is not contagious. No one can "catch" this disease from another person.
Research has shown that people with certain risk factors are more likely than others to develop this type of cancer. A risk factor is anything that is linked to an increased chance of developing a disease.
Studies have identified the following colon cancer risk factors:
- Age (risk increases as people get older)
- Colorectal polyps
- Family history of colon cancer
- Personal history of colon cancer
- Certain medical conditions (like ulcerative colitis and Crohn's disease)
- Certain diets (such as diets that are high in fat and low in fiber)
Colon cancer is more likely to occur as people get older. More than 90 percent of people with this disease are diagnosed after age 50. The average age at diagnosis is in the mid-60s.
Polyps are growths on the inner wall of the colon or rectum. Most polyps are benign (noncancerous), but some polyps (adenomas) can turn into cancer. Finding and removing polyps may reduce the risk of colon cancer.
There are several types of polyps, and they become increasingly common with age. By age 50, 10 percent of the population has polyps, but that number grows to 30 percent by age 65. If left untreated, 8 to 12 percent of polyps will become cancerous. If allowed to grow, the tumor can invade nearby organs.
Once the disease enters the lymph nodes or bloodstream, it most often spreads to the liver.