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Siteman Cancer Center at Barnes-Jewish Hospital and Washington University School of Medicine

Fact sheet

What is the colon?
What is colon cancer?
How common is colon cancer?
Who is at risk of getting colon cancer?
How do you prevent colon cancer?
Who should get screened for colon cancer?
What are the symptoms of colon cancer?
Where can I get more information?

What is the colon?
The colon is the main part of the large intestine, which is the long, muscular tube that food passes through during digestion.

What is colon cancer?
Colon cancer occurs when cells in the colon grow out of control. A group of abnormal cells together can form a growth in the colon called a polyp.  If not removed, cells in the polyp can continue to grow, turn into cancer, and spread.

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How common is colon cancer?
Colon cancer is the fourth most common cancer in the US, and it is the number one cause of cancer death in nonsmokers.To compare this with other cancers, click here.

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Who is at risk of getting colon cancer?
Anyone can get colon cancer; it strikes both men and women. Colon cancer is more common in people over 50, and people with a family history of colon cancer have a higher chance of getting the disease.

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How do you prevent colon cancer?
  • Get regular screening tests beginning at age 50 (or earlier if you have a family history.)
  • Be physically active for at least 30 minutes every day
  • Maintain a healthy weight
  • Limit the amount of alcohol you drink
  • Limit red meat to less than 3 servings a week
  • Take a multivitamin with folate every day
  • Make sure you get enough calcium and vitamin D
  • Take an aspirin every day (check with your doctor first)
Click here for a list of things that affect colon cancer risk.

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Who should get regular screening tests for colon cancer?

Everyone (men and women) should be screened regularly for colon cancer starting at age 50. People who have a family history of colon cancer and people who have certain disease, like inflammatory bowel disease, may need to start screening before age 50.


Getting regular screening tests is the single best way to lower colon cancer risk. Screening tests can prevent colon cancer by finding polyps.  Polyps are small abnormal growths that can sometimes turn into cancer.  If they are found early, polyps can be removed before cancer develops.  If cancer has already developed, screening can help find it at an early stage, when it can be most successfully treated.

Click here for more information on colon cancer screening.

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What are the symptoms of colon cancer?

Colon cancer may cause no symptoms at all in the early stages. That’s why screening is very important: to find any abnormal changes before they develop and spread.

As the cancer grows, symptoms may include:

  • A change in bowel habits, like increased constipation or diarrhea
  • A change in the way bowel movements look
  • Blood in bowel movements
  • Abdominal pain
These symptoms also may be caused by other problems. Only a doctor can know for sure. If you have any of these symptoms, see a doctor immediately.

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For more information on colon cancer, visit these web sites: Back to top