Please note: This information was current at the time of publication. But medical information is always changing, and some information given here may be out of date. For regularly updated information on a variety of health topics, please visit, the AAFP patient education website.

Information from Your Family Doctor

Colon Cancer Screening: What You Should Know


Am Fam Physician. 2015 Jan 15;91(2):online.

  See related article on colorectal cancer screening

What is colon cancer?

The colon, also called the large intestine, is a long tube that carries digested food from the small intestine to the anus. Colon cancer is an abnormal growth that can begin anywhere in the colon. It can spread to other parts of the body and lead to death. Colon cancer is common in both men and women.

What are the symptoms of colon cancer?

Symptoms of colon cancer include blood in the stool; dark, tarry stool; stomach pain; or a change in bowel habits. Most people have no symptoms early in the disease, so routine screening for colon cancer is important.

When and how should I be tested?

Most people should begin colon cancer screening at 50 years of age; some doctors recommend that black people begin at 45 years of age because they are more likely to get the disease. Healthy people should have screening tests until they are at least 75 years old. There are several kinds of screening tests, including stool testing, CT, and colonoscopy (coh-lo-NOS-co-pee). If you have a parent or sibling who had colon cancer when he or she was younger than 60 years, you should have a colonoscopy at 40 years old, or when you are 10 years younger than the age the family member was when diagnosed, whichever is earlier.

What is a colonoscopy?

A colonoscopy is a test where a doctor looks inside the colon by putting a long flexible tube with a tiny video camera into the rectum. During this test, your doctor can remove growths, called polyps (PAW-lips), from your colon. Some polyps are not harmful. Other polyps can turn into cancer. If your doctor removes this type, you will need another colonoscopy earlier than usual to look for similar polyps that may grow.

How often should I get a colonoscopy?

Several medical groups have joined together to issue guidelines on how often people should have a follow-up colonoscopy. These groups include the American Cancer Society, the American College of Radiology, the American College of Gastroenterology, the American Gastroenterological Association Institute, and the American Society for Gastrointestinal Endoscopy. How often you should have a colonoscopy depends on the results of your first test.

You should have your next colonoscopy in 10 years if your first test shows:

  • No polyps (a normal test) and you have no family history of colon cancer

  • Hyperplastic polyps; these polyps are usually small and rarely turn into colon cancer

You should have your next colonoscopy in five to 10 years if your first test shows:

  • One or two tubular adenomas (ad-uh-NO-muhs) smaller than 10 mm; adenomas sometimes turn into colon cancer

You should have your next colonoscopy in three years if your first test shows:

  • Three to 10 tubular adenomas

  • Any tubular adenoma larger than 10 mm

  • An advanced polyp

You should have your next colonoscopy in less than three years if:

  • Your first test shows more than 10 adenomas

  • You had a large polyp that was not completely removed (colonoscopy should be repeated in less than one year)

  • You recently had surgery to remove colon cancer (colonoscopy should be repeated one year after surgery)

This handout is provided to you by your family doctor and the American Academy of Family Physicians. Other health-related information is available from the AAFP online at

This information provides a general overview and may not apply to everyone. Talk to your family doctor to find out if this information applies to you and to get more information on this subject.


Copyright © 2015 by the American Academy of Family Physicians.
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