cancer (cancer of the colon or rectum) is the second leading cause
of cancer deaths in the United States. It is estimated that in
2006, about 145,000 new cases will be diagnosed and about 56,000
people will die of this disease. Among men, colorectal cancer is
the third most commonly occurring cancer (after lung and prostate
cancer) and among women it ranks third (after lung and breast cancer).
Who Is at Risk for Colorectal Cancer?
Most cases of colorectal cancer are diagnosed in individuals past
the age of 50, with the average age of diagnosis being 70 for
men and 73 for women. Age is considered a significant risk factor
for developing this disease. Therefore, the American Cancer Society
recommends routine screening for colorectal cancer for everyone
over 50 years of age (see table for screening guidelines).
Regardless of age, there are certain people that are more likely
to develop colorectal cancer. For example, certain hereditary colon
conditions and certain types of non-cancerous colon disease can
increase the risk of colorectal cancer. Having a relative with
colorectal cancer also increases the risk. The screening guidelines
for individuals at increased risk are somewhat different than for
those over 50 years old who are at average risk (that is, without
one of these identifiable risk factors).
How do you screen for colorectal cancer?
goal of screening for colorectal cancer is to find the cancer at
an early stage when it is more likely to be cured. It is believed
that most colorectal cancers originate as growths of the intestinal
lining of the colon or rectum, called polyps. Polyps usually have
a slender stem with a tuft of tissue at the end of the stem. If
a cancer can be prevented by finding and removing polyps that might
eventually become cancerous, then this would fit the criteria for
an ideal screening method. But how can a polyp be found? It is
known that blood vessels around polyps are somewhat fragile and
easily damaged by the passage of stool. The damaged vessels can
release a small amount of blood into the stool. There is a test
called the fecal occult blood test (FOBT), sometimes referred to
as a “stool test,” which
attempts to detect occult (hidden) blood present in the stool.
A small amount of stool is obtained and smeared onto a special
type of paper card. A few drops of a special chemical liquid
are added to the card and if there is blood in the stool, the
card will turn into a particular color. WHPP participants can
get this type of colorectal cancer screening test as part of
their free physical exam.
There are other screening options recommended by
the American Cancer Society, including sigmoidoscopy and colonoscopy.
A sigmoidoscopy is performed with a sigmoidoscope,which is a slender,
flexible, hollow, lit tube about the thickness of a finger. It
is inserted through the rectum to view the rectum and colon. The
sigmoidoscope is about two feet long and can view only a portion
of the colon (the colon is about five feet long). A colonoscopy
is performed with a colonoscope (a longer version of the sigmoidoscope),
which allows for viewing of the entire colon. These screening tests
can be uncomfortable and involve somewhat greater risks than a “stool
CANCER SOCIETY COLORECTAL
at age 50, men and women who are at average risk for developing
colorectal cancer should have 1 of the 5 screening options
|Fecal occult blood test (FOBT)*
fecal immunochemical test (FIT)
||Every 5 years
|FOBT* or FIT every year
(of these first 3 options,
is the most preferable
|Every 5 years
|Double-contrast barium enema
(an x-ray study)
|Every 5 years
||Every 10 years
What if the stool test is abnormal?
The stool test cannot tell whether blood is from the colon or from
other parts of the digestive tract. If this test is positive
for the presence of blood, additional testing such as a colonoscopy
is usually needed to determine the source of the blood. If polyps
or other abnormalities are found (such as a tumor), they are
removed and then sent to a lab to be tested to see if they are
It is important to keep in mind that an abnormal
stool test does not automatically signify cancer and can be related
to other conditions such as hemorrhoids or ulcers. Therefore, although
it is true that this screening method can produce abnormal results
without cancer being present, the stool test is not invasive and
can be easily and readily performed. Furthermore, this test has been
widely studied and used as a screening method and has been proven
to help reduce colon cancer deaths in large population groups, both
in the U.S. and internationally.