Experts said the study, conducted in Norway and reported in the Aug. 13 issue of the Journal of the American Medical Association, confirms the value of sigmoidoscopy screening.
But
in the United States, where few doctors even perform sigmoidoscopy, the
results are unlikely to make a difference in everyday practice.
in the United States, where few doctors even perform sigmoidoscopy, the
results are unlikely to make a difference in everyday practice.
"Sigmoidoscopy
is definitely second-best to colonoscopy," said Dr. James Church, a
colorectal surgeon at the Cleveland Clinic in Ohio.
is definitely second-best to colonoscopy," said Dr. James Church, a
colorectal surgeon at the Cleveland Clinic in Ohio.
That's mainly
because sigmoidoscopy looks only at the lower portion -- or "left side"
-- of the colon, said Church, who was not involved in the study.
Colonoscopy gives doctors a view of the entire colon.
because sigmoidoscopy looks only at the lower portion -- or "left side"
-- of the colon, said Church, who was not involved in the study.
Colonoscopy gives doctors a view of the entire colon.
Both
procedures not only detect cancer but also help prevent it -- by
allowing doctors to remove potentially precancerous growths called
polyps. But colonoscopy can pick up polyps throughout the colon.
procedures not only detect cancer but also help prevent it -- by
allowing doctors to remove potentially precancerous growths called
polyps. But colonoscopy can pick up polyps throughout the colon.
"Colonoscopy is not perfect, by any means," Church said. But, he added, "if you don't want to get colon cancer, colonoscopy is the best option."
The
new trial was conducted in Norway, where there is no routine colon
cancer screening, explained lead researcher Dr. Oyvind Holme, of
Sorlandet Hospital in Kristiansand, Norway.
new trial was conducted in Norway, where there is no routine colon
cancer screening, explained lead researcher Dr. Oyvind Holme, of
Sorlandet Hospital in Kristiansand, Norway.
That allowed the
researchers to offer one-time sigmoidoscopy screening to over 20,000 50-
to 64-year-old adults, then compare them with 78,000 people the same
age who were not offered any kind of colon cancer screening.
researchers to offer one-time sigmoidoscopy screening to over 20,000 50-
to 64-year-old adults, then compare them with 78,000 people the same
age who were not offered any kind of colon cancer screening.
Half
of the sigmoidoscopy group also received a stool test to look for hidden
blood -- another option for colon cancer screening.
of the sigmoidoscopy group also received a stool test to look for hidden
blood -- another option for colon cancer screening.
Holme's team
found that people who underwent screening were 27 percent less likely to
die of colon cancer over the next decade, versus the unscreened group.
found that people who underwent screening were 27 percent less likely to
die of colon cancer over the next decade, versus the unscreened group.
According to Holme, the findings bolster evidence that sigmoidoscopy is a "valuable tool" for colon cancer screening.
But,
he said, they don't mean that sigmoidoscopy is the best tool. "We did
not compare flexible sigmoidoscopy to other screening methods," Holme
pointed out.
he said, they don't mean that sigmoidoscopy is the best tool. "We did
not compare flexible sigmoidoscopy to other screening methods," Holme
pointed out.
In the United States, experts advise most people to begin colon cancer screening at age 50.
The
U.S. Preventive Services Task Force recommends three choices: an annual
stool test; sigmoidoscopy every five years, along with stool testing
every three years; or colonoscopy every 10 years.
U.S. Preventive Services Task Force recommends three choices: an annual
stool test; sigmoidoscopy every five years, along with stool testing
every three years; or colonoscopy every 10 years.
In practice, though, colonoscopy is by far the most common test in the United States.
Sigmoidoscopy
does have a number of advantages over colonoscopy, Holme said. The
pre-exam bowel cleanse is easier to take, and the procedure itself is
faster, does not require sedation and can be done by a primary care
doctor or trained nurse -- whereas colonoscopies are done by
gastroenterologists.
does have a number of advantages over colonoscopy, Holme said. The
pre-exam bowel cleanse is easier to take, and the procedure itself is
faster, does not require sedation and can be done by a primary care
doctor or trained nurse -- whereas colonoscopies are done by
gastroenterologists.
Sigmoidoscopy is also much cheaper: In the United States, it costs about $150 to $300, versus $1,000 or more for a colonoscopy.
But
some of those advantages are not as good as they sound, according to
Church. Since patients are not sedated for sigmoidoscopy, he said, it's
actually more uncomfortable than colonoscopy, for example.
some of those advantages are not as good as they sound, according to
Church. Since patients are not sedated for sigmoidoscopy, he said, it's
actually more uncomfortable than colonoscopy, for example.
What
this study shows, Church said, is that sigmoidoscopy is better than no
screening -- for preventing cancers on the left side of the colon.
this study shows, Church said, is that sigmoidoscopy is better than no
screening -- for preventing cancers on the left side of the colon.
Among
patients who were screened, there were 113 cancers per 100,000 people
each year of the study. That compared with 141 per 100,000 in the
unscreened group. But the difference was mostly seen in cancers in the
left side of the colon.
patients who were screened, there were 113 cancers per 100,000 people
each year of the study. That compared with 141 per 100,000 in the
unscreened group. But the difference was mostly seen in cancers in the
left side of the colon.
"For right-sided colon cancer, sigmoidoscopy is, statistically, the same as doing nothing," Church said.
In
the end, questions over how sigmoidoscopy fits into colon cancer
screening could actually be moot in the near future, according to an
editorial published with the study.
the end, questions over how sigmoidoscopy fits into colon cancer
screening could actually be moot in the near future, according to an
editorial published with the study.
New DNA stool tests, which are
much more precise than standard stool tests, have the potential to
reduce routine colonoscopies, writes Dr. Allan Brett, of the University
of South Carolina School of Medicine in Columbia.
much more precise than standard stool tests, have the potential to
reduce routine colonoscopies, writes Dr. Allan Brett, of the University
of South Carolina School of Medicine in Columbia.
"Fecal DNA tests
could change the way we think about stool testing," Church said.
"They're so much better than what we have now."
could change the way we think about stool testing," Church said.
"They're so much better than what we have now."
Just yesterday,
the U.S. Food and Drug Administration approved a DNA-based stool test
that detects colon cancer with more than 90 percent accuracy. Still,
experts said, the test is not intended to replace colonoscopies -- and
any positive result would have to be followed up with a colonoscopy to
confirm the diagnosis.
the U.S. Food and Drug Administration approved a DNA-based stool test
that detects colon cancer with more than 90 percent accuracy. Still,
experts said, the test is not intended to replace colonoscopies -- and
any positive result would have to be followed up with a colonoscopy to
confirm the diagnosis.
The hope is that new and better options
will encourage more people to get screened. A recent government study
found that one-third of Americans eligible for colon cancer screening
aren't doing it.
will encourage more people to get screened. A recent government study
found that one-third of Americans eligible for colon cancer screening
aren't doing it.
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