Colorectal Cancer - Causes

Researchers do not know the cause of colorectal cancer. But they do know that certain risk factors make it more likely that a person will develop the condition. These risk factors include:

• Family history. About 10 percent of all cases of colorectal cancer are thought to be hereditary. People whose family members have had the disorder are more likely to contract it themselves.
• History of colorectal cancer. Some people contract colorectal cancer more than once. New cancers develop in areas other than those in which the cancer first appeared.
• Recurrent intestinal polyps. Most polyps are benign. However, some people tend to get polyps frequently on the lining of their intestines. People with this tendency are at higher risk for colorectal cancer.
• Inflammatory bowel disease. Inflammatory bowel disease refers to a number of different conditions in which the colon becomes irritated and inflamed. Ulcers (open sores; see ulcers entry) often develop on the lining of the bowel. This pattern can increase the risk of colorectal cancer.
• Age. The risk of having colorectal cancer increases with age. About 90 percent of all cases are diagnosed in people over the age of fifty.
• Diet. Eating foods that are high in fat and/or low in fiber may increase the risk of colorectal cancer.
• Physical inactivity. People who tend to be less active are at greater risk for colorectal cancer.