Risk Factors for Colorectal Cancer

75% of Colorectal Cancers occur in people with no known risk factors. There is strong scientific evidence that having regular screening tests beginning at age 50 reduces deaths from colorectal cancer. Screening tests can find precancerous polyps (abnormal growths) in the colon and rectum, and remove them before they turn into cancer.

Who’s at risk?

Everyone.

On average 1 in 11 people will be diagnosed with colon cancer.

• Affects both men and women
• It is most often found in people 50 or older
• Risk increases with age

Some factors increase your risk for colorectal cancer including:

• Age (50+) is the biggest risk factor. Colorectal cancer, like many other cancers, is more likely to occur as people get older. More than 90% of cases occur in people aged 50 or older. The average age of diagnosis is 72.
• Having had polyps or colorectal cancer before. Polyps, growths in the inner wall of the colon or rectum are common in people over 50. Most polyps are benign (not cancerous), but some polyps can become cancer. Some types of polyps increase the risk of colorectal cancer, especially is they are large or if there are many of them. If you have had colorectal cancer before (even if it has been completely removed.)
• Family history of Colorectal Cancer or Polyps. Close relatives (parents, brother, sisters, or children) of a person with a history of colorectal cancer or polyps are at increased risk, especially if the relative had the cancer at a young age.
• Genetic syndrome such as familial adenomatous polyposis (FAP) or hereditary nonpolyposis colorectal cancer (Lynch Syndrome).
• Having inflammatory bowel disease such as Crohn’s Disease or ulcerative colitis.
• History of other cancers, especially endometrial cancer.
• Race or ethnic background. African-Americans have the highest risk of any ethnic group in the US. Jews of Eastern European decent (Ashkenazi Jews) have one of the highest risks of colon cancer of any ethnic group in the world.
• Lifestyle factors can also contribute to increased risk for colorectal cancer including:
  • Lack of regular physical activity
  • A low-fiber and high-fat diet (especially animal)
  • Low fruit and vegetable intake
  • Being overweight or obese
  • Alcohol consumption
  • Tobacco use

If you are in a higher risk category you may need earlier or more frequent tests than people who are at average risk. Talk to your doctor about when to begin screening, which screening test is right for you and how often you should be tested.

The National Institute of Health developed an online colorectal cancer risk assessment tool for people over 50. Take the online assessment by visiting www.Cancer.gov/ColorectalCancerRisk.

The two most important things you can do to reduce your risk for colorectal cancer are to get screened and follow your doctor’s recommendations for follow-up. Talk to your doctor about which screening test is right for you.

More on risk factors on the web:

American Cancer Society - Information and resources for colon and rectal cancer including a look at risk factors.