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JAMA Patient Page
March 8, 2006

Colon Cancer Screening

JAMA. 2006;295(10):1208. doi:10.1001/jama.295.10.1208

Colon cancer (cancer of the large bowel) is the second leading cause of cancer deaths in the United States, exceeded only by lung cancer. Colon cancer can be treated and often cured if it is found early. Because death from colon cancer is preventable, doctors want to look for colon cancer before it grows too large or spreads to other organs. Testing persons without symptoms or signs of colon cancer (such as blood in the stool or low blood count) is called screening. Screening for colon cancer is recommended for everyone aged 50 years and older.

The March 8, 2006, issue of JAMA includes an article about screening for colon cancer. This Patient Page is based on one previously published in the March 12, 2003, issue of JAMA.

Methods for screening

  • Fecal occult blood test
    Colon cancer can cause a small amount of occult (not visible) bleeding. Testing for this occult blood involves placing a small sample of feces on a card and then adding a chemical solution. If the result indicates the presence of occult blood, further testing is required to determine the source of bleeding. This test is simple to perform but will not detect all colon cancers.

  • Flexible sigmoidoscopy
    The sigmoid colon is the lowest part of the colon, near the rectum (the last several inches of the large bowel). Sigmoidoscopy is the placement of a lighted tube into the rectum after enemas to cleanse the lower part of the bowel. This tube is gently moved forward into the sigmoid colon. The walls of the sigmoid colon are then examined for abnormal growths.

  • Colonoscopy
    If your doctor recommends colonoscopy (for screening or if growths are found on sigmoidoscopy), you will consume only clear liquids and take laxative solutions to cleanse your intestinal tract (bowels) during the day before the procedure. Colonoscopy is not painful but is uncomfortable enough that you may require sedative medication during the procedure. The doctor will insert the colonoscope (a lighted tube with a camera on the end) through your rectum while you rest on your side. The camera will display its picture on a monitor screen. The colonoscope is gently pushed forward through as much of the colon as possible. If the doctor finds any suspicious areas in the colon, biopsies (tissue samples) may be taken. Colon polyps (small growths) can also be removed through the colonoscope.

  • Barium enema—a type of x-ray procedure that requires preparation similar to that for colonoscopy.

For more information

Inform yourself

To find this and previous JAMA Patient Pages, go to the Patient Page link on JAMA's Web site at Many are available in English and Spanish. A Patient Page on colon cancer was published in the December 20, 2000, issue.

Sources: American Cancer Society, National Cancer Institute, American Gastroenterological Association, American Society for Gastrointestinal Endoscopy

The JAMA Patient Page is a public service of JAMA. The information and recommendations appearing on this page are appropriate in most instances, but they are not a substitute for medical diagnosis. For specific information concerning your personal medical condition, JAMA suggests that you consult your physician. This page may be photocopied noncommercially by physicians and other health care professionals to share with patients. To purchase bulk reprints, call 203/259-8724.