A risk factor is something that increases your chances of developing cancer.

It is possible to develop colorectal cancer with or without the risk factors listed below. However, the more risk factors you have, the greater your likelihood of developing colorectal cancer. If you have a number of risk factors, ask your health care provider what you can do to reduce your risk.

Colon Cancer

Colon Cancer
© 2009 Nucleus Medical Art, Inc.

Risk factors for colorectal cancer include the following:

Genetic Factors

Heredity is perhaps the strongest risk factor for developing colorectal cancer. It is estimated that approximately 20% of all cases of colorectal cancer are hereditary. This risk increases if you have a primary relative (parent, sibling, child) who develops colorectal cancer.

The two most common forms of inherited colon cancer are hereditary non-polyposis colon cancer (HNPCC) and familiar adenomatous polyposis (FAP).


Colorectal cancer most commonly occurs after age 50, though certain forms of this cancer may develop earlier. However, colorectal cancer can occur at any age.

Lifestyle Factors

Colorectal cancer has been strongly associated with lifestyle factors. The following factors may increase your risk of developing colorectal cancer:


Diets high in fat (particularly fat from animal sources) and low in fiber have been associated with increased risk of colorectal cancer. Eating a diet that is high in fruits and vegetables may help lower the risk.

Lack of Exercise

Regular exercise has been shown to decrease the risk of developing colorectal cancer. Moderate exercise (30 minutes per day) is beneficial.


Obesity increases the risk of colorectal cancer, particularly when excess weight is carried at the waist, rather than on the hips and thighs.


Smokers are 30% to 40% more likely to die of colorectal cancer than nonsmokers.


Regular use of alcohol in smokers and people with high fat diets appears to increase the risk of colorectal cancer. However, there does not seem to be an increased risk in people who drink alcohol, but eat diets high in fiber.


Both men and women develop colorectal cancers. However, men are at slightly higher risk for developing rectal cancers, and women are at slightly higher risk for developing colon cancer.

Medical Conditions

The following medical conditions have been shown to increase the risk of developing colorectal cancer:

  • Ulcerative colitis – a severe, chronic inflammatory bowel disease. It causes inflammation, ulcers, and bleeding in the lining of the colon and rectum.
  • Crohn’s disease – a severe, chronic inflammatory bowel disease. It causes inflammation, ulcers, and bleeding in any part of the digestive tract from the mouth to the anus.
  • Gardner’s syndrome – a genetic disease that causes the growth of non-cancerous (benign) polyps in the intestine.   
  • Polyps – small growths inside the intestines
  • Other types of cancer:
    • Ovarian
    • Uterine
    • Breast
    • Previous colorectal cancer

Ethnic Background

Incidence of colorectal cancer is most prevalent in "Westernized" countries. In the U.S., the rate is slightly higher for blacks than for whites. An increased risk of colon cancer has also been noted in Jewish people of Eastern European descent.