Causes and Risk Factors of Colorectal Cancer

Research has shown that people with certain risk factors are more likely than others to develop colon and rectal (colorectal) cancer. Some factors like diet and lifestyle choices can be adjusted to reduce risk. Others, such as age and family history, can’t be changed. Regardless, it’s important to understand the various factors that can increase your risk for colon and rectal cancers.

Colorectal cancer risk factors you can control include:

  • Weight.  Being overweight or obese, especially when the majority of the weight is in your middle, can raise the risk of colorectal cancer in both men and women.
  • Lack of exercise.  Physical inactivity can put you at an increased risk.
  • Diet.  High consumption of red meat (beef, pork, lamb, or liver) and processed meats (i.e. hot dogs; luncheon meats) can raise your risk of colorectal cancer. Adding more fruits, vegetables, and whole grain fibers has been shown to lower the risk.
  • Smoking.  While smoking is a common cause of lung cancer, it has also been linked to other cancers, such as colon cancer.
  • Alcohol use.  Colorectal cancer has been linked to heavy alcohol consumption. The risk can greatly decrease by limiting alcohol use to no more than 1 to 2 drinks per day.

Colorectal cancer risk factors that cannot be controlled include:

  • Age.  Colon and rectal cancers are less common in young adults. It is much more common among men and women age 50 and older.
  • Personal medical history.  Certain medical conditions such as adenomatous polyps (adenomas) and inflammatory bowel disease (including ulcerative colitis or Crohn’s disease) can increase the risk of colorectal cancer.
  • Family history.  Cancers can sometimes “run in the family” because of inherited genes, shared environmental factors, or a combination of both. If you have a family history of adenomatous polyps or colorectal cancer, you may want to ask your doctor if you should be screened at an earlier age or if genetic testing is right for you, so that you can learn more about your hereditary risk for developing colorectal cancer.
  • Race/Ethnicity.  People of African American descent and Jews of Eastern European descent (Ashkenazi Jews) are at more risk to develop colorectal cancer than people of other races.
  • Diabetes.  The risk of colorectal cancer is increased among people with type 2 diabetes. Patients with type 2 diabetes also tend to have poorer outcomes from the colorectal cancer treatment.

If you have one or more risk factors it doesn’t mean that you will definitely develop colon or rectal cancer. Likewise, not having risk factors does not mean you will not get it.  Be sure to talk with your doctor if you think you may be at risk and begin regular screening for colon cancer by age 45 – even if you have no known risk factors.