NEW YORKTo increase colorectal cancer screening, the
American Cancer Society (ACS) is encouraging the use of at least one of the
four recommended screening tests. Previously, for persons of average risk,
annual fecal occult blood test (FOBT) and flexible sigmoidoscopy every 5 years
were only recommended in combination.
The updated guidelines state that annual FOBT plus flexible
sigmoidoscopy every 5 years is preferred over either test alone, but the
rationale for the new option is that any test alone is far better than not
being screened at all, Robert A. Smith, PhD, the ACS’s director of Cancer
Screening, said at a Cancer Research Foundation of America (CRFA) press
briefing on colorectal cancer.
Extensive research by the ACS, Dr. Smith said, "made clear
that the nation at this point in time is not prepared to fulfill a . . . requirement of annual FOBT and flexible sigmoidoscopy every 5 years." If
primary care providers are "not prepared to offer the full range of
options, we strongly encourage them to just do something," he said.
Alternative but more complex screening options for the
average-risk individual, starting at age 50, are double-contrast barium enema
every 5 years or colonoscopy every 10 years, he said.
Dr. Smith called annual FOBT "a very effective screening
test." Although it is not the most effective screening test, "we
could reduce colorectal cancer mortality by 30% or more if people would just do
this one simple test every year," he said.
Doing the FOBT in a physician’s office with a single stool
sample is not recommended, Dr. Smith stressed. Instead, samples from three
consecutive bowel movements should be applied to a card that is then forwarded
to a physician or laboratory for processing.
"Because cancers tend to bleed intermittently," he
explained, "it’s very important to collect the full three samples."
A test based on a single sample after a digital rectal examination, he noted,
has limited sensitivity and will detect only half the cancers present in
He noted that unlike most false-positive screening tests, a
false-positive FOBT "offers something back." When a patient is
referred to colonoscopy because of a positive FOBT and the colonoscopy does not
reveal any important lesions, he said, "that person does not require any
further colon screening for another decade."
Recent studies suggest that more than 80% of the important
lesions throughout the colon could be picked up simply by doing flexible
sigmoidoscopy, he said. The reach of a flexible sigmoidoscopy is about halfway
into the colon under the best of circumstances, he noted, but if significant
lesions are detected in the distal colon, they are likely to be present
throughout the colon, and thus a colonoscopy should be performed.
Dr. Smith called colonoscopy "the Cadillac" of
colorectal cancer screening tests. "It provides the opportunity to detect
not only cancers but also adenomatous polyps and to remove them for biopsy all
at the same examination." The recommended 10-year interval for colonoscopy in average-risk individuals, he noted, is based on the estimated
10-year "dwell time" for a polyp of less than 1 cm to become
For people at increased or high risk of colorectal cancer,
colonoscopy remains the recommended screening examination, starting at an
earlier age and at different intervals, depending on the person’s risk
If double-contrast barium enema is used, the guidelines now
recommend that it be performed every 5 years instead of every 5 to 10 years.
"We reduced the interval for the barium enema because of new data showing
that it is somewhat less sensitive than previously thought," he said.
Barium enema may be good for patients who cannot tolerate or have an aversion
to endoscopy. For the full recommendations, see www.cancer.org.