What are the risk factors for colorectal cancer?
The exact causes of colorectal cancer are not known. However, studies have shown that certain factors are linked to an increased chance of developing this disease , including the following:

Older age. About 90 percent of people diagnosed with colon cancer are older than 50. Colon cancer can occur in younger people, but it occurs much less frequently.
African-American race. African-Americans have a greater risk of colon cancer than do people of other races.
A personal history of colorectal cancer or polyps. If you’ve already had colon cancer or adenomatous polyps, you have a greater risk of colon cancer in the future.
Inflammatory intestinal conditions. Chronic inflammatory diseases of the colon, such as ulcerative colitis and Crohn’s disease, can increase your risk of colon cancer.
Inherited syndromes that increase colon cancer risk. Genetic syndromes passed through generations of your family can increase your risk of colon cancer. These syndromes include familial adenomatous polyposis and hereditary nonpolyposis colorectal cancer, which is also known as Lynch syndrome.
Family history of colon cancer and colon polyps. You’re more likely to develop colon cancer if you have a parent, sibling or child with the disease. If more than one family member has colon cancer or rectal cancer, your risk is even greater. In some cases, this connection may not be hereditary or genetic. Instead, cancers within the same family may result from shared exposure to an environmental carcinogen or from diet or lifestyle factors.
Low-fiber, high-fat diet. Colon cancer and rectal cancer may be associated with a diet low in fiber and high in fat and calories. Research in this area has had mixed results. Some studies have found an increased risk of colon cancer in people who eat diets high in red meat.
A sedentary lifestyle. If you’re inactive, you’re more likely to develop colon cancer. Getting regular physical activity may reduce your risk of colon cancer.
Diabetes. People with diabetes and insulin resistance may have an increased risk of colon cancer.
Obesity. People who are obese have an increased risk of colon cancer and an increased risk of dying of colon cancer when compared with people considered normal weight.
Smoking. People who smoke cigarettes may have an increased risk of colon cancer.
Alcohol. Heavy use of alcohol may increase your risk of colon cancer.
Radiation therapy for cancer. Radiation therapy directed at the abdomen to treat previous cancers may increase the risk of colon cancer.