Colon cancer (cancer of the large bowel) strikes 155,000 persons in the United
States each year. It 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 12, 2003, issue of JAMA includes 2 articles about screening
for colon cancer.
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.
colon is the lowest part of the colon, near the rectum (where feces
leaves the body). 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.
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.
This will allow the doctor to view the walls of the intestine without blockage
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 for the doctor to see. 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 (samples) may be taken.
Colon polyps (small growths) can also be removed through the colonoscope.
Double-contrast barium enema (a type of x-ray procedure)
American Cancer Society 800/227-2345 www.cancer.org
National Cancer Institute 800/422-6237 www.nci.nih.gov/cancer_information/cancer_type/colon_and_rectal
American Gastroenterological Association
To find this and previous JAMA Patient Pages, go to the
Patient Page Index on JAMA ’s Web site at www.jama.com
. They 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
Endoscopic image courtesy of Arnold J. Markowitz, MD
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
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Colon Cancer Screening. JAMA. 2003;289(10):1334. doi:10.1001/jama.289.10.1334