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Colorectal Cancer Causes & Risk Factors

There are many different causes and risk factors for colorectal cancer. Sometimes, a person with no known risk factors can be diagnosed with the disease. However, there are certain factors that can put you at greater risk.

Some colorectal cancer risk factors are beyond your control. But some, like diet and exercise, are within you power to change. Talk to your doctor about making healthy lifestyle changes to lower your risk of getting colon cancer.

Causes and risk factors include:

  • Age: The chances of having colorectal cancer increase after age 50. More than nine out of 10 people with colorectal cancer are older than 50.
  • Previous polyps or colorectal cancer: Some polyps increase the risk of colorectal cancer, especially if they are large or if there are many of them. Previous instances of colorectal cancer (even if completely removed) make new cancers more likely to occur in other areas of your colon and rectum. These chances increase if you had your first instance at a relatively young age.
  • History of bowel disease: Inflammatory bowel diseases, like ulcerative colitis and Crohn's disease, increase your risk of colon cancer. Irritable bowel syndrome (IBS) is different from inflammatory bowel disease and does not increase colorectal cancer risk.
  • Family history of colorectal cancer: If you have close relatives with this cancer, your risk might be increased, especially if the family member got the cancer at a relatively young age.
  • Race or ethnic background: Some racial and ethnic groups, such as African Americans and Jews of Eastern European descent, have a higher colorectal cancer risk. Among Ashkenazi Jews, scientists have found several gene mutations that lead to an increased risk of colorectal cancer.
  • Certain types of diets: A diet high in red meats and processed meats can increase your colorectal cancer risk. Cooking meats at high heat (frying, broiling or grilling) generates chemicals that might increase cancer risk. Diets high in vegetables and fruits can lower risk of colorectal cancer.
  • Lack of exercise: Exercise may help reduce your risk.
  • Overweight: Maintaining a healthy weight decreases a person's risk of having and dying from colorectal cancer.
  • Smoking: Long-time smokers are more likely to have and die from colorectal cancer.
  • Alcohol: Studies have linked heavy alcohol use to colorectal cancer.
  • Diabetes: People with Type 2 diabetes have an increased chance of getting colorectal cancer. They also tend to have poorer outcomes.