Virtual
Colonoscopy Finds Colorectal Cancer, Study Shows
New CT Scans Use
3-D Images
Virtual colonoscopy
compares favorably to the current "gold standard" of conventional
colonoscopy, according to a report in the New England
Journal of Medicine.
The procedure, using
3-D imaging technology, may eventually convince experts
that virtual colonoscopy is a reliable screening tool.
"We have proved that
virtual colonoscopy is a viable screening option," says lead
researcher Dr. Perry J. Pickhardt, an associate professor of
radiology at the University of Wisconsin Medical School.
Standard colonoscopy
is a procedure that allows the physician to view the entire
length of the large intestine, and can often help identify abnormal
growths such as polyps, inflamed tissue, ulcers, and bleeding.
This test involves
inserting a colonoscope, a long, flexible, lighted tube, in
through the rectum up into the colon. The colonoscope allows
the physician to see the lining of the colon, remove tissue
for further examination, and possibly treat some problems that
are discovered. Patients are usually sedated during the procedure.
The virtual colonoscopy,
however, is completely noninvasive. In this procedure, usually
a spiral CT scan is taken of the gastrointestinal area, and
then a computer puts together an image of the person's colon
for examination by a radiologist.
Study
Use of 3-D Imaging Aids Accuracy
In the latest study,
Dr. Pickhardt's team had 1,233 asymptomatic men and women undergo
virtual and conventional colonoscopies. All the participants
were considered at low risk for the disease.
To the surprise of
Dr. Pickhardt's group, both methods were equally accurate. However,
one of two malignant polyps detected in this experiment was
missed by the conventional colonoscopy.
"Our 3-D approach
really set us apart from other studies and is most likely the
reason that previous studies using non-3-D CT to detect colorectal
cancer were so disappointing," Dr. Pickhardt says.
In addition, using
state-of-the-art CT equipment and the way the patients were
prepared for the procedure added to the accuracy of
virtual colonoscopy, he says.
The researchers suggest
that the individuals most likely to benefit from virtual
colonoscopy are those with the lowest risk of colorectal
cancer, usually people with no family history of colorectal
cancer.
Individuals with
a higher risk should have a conventional colonoscopy, the researchers
say. If a polyp is found by a virtual colonoscopy, the patient
would have to undergo a conventional colonoscopy to have the
polyp removed, Dr. Pickhardt notes.
Based on these results,
"virtual colonoscopy should join conventional colonoscopy as
a major component of colorectal cancer screening," he says.
Dr. Pickhardt hopes
this new screening technique will encourage more people to get
screened. He points out that while colorectal cancer is the
second leading cause of cancer deaths in the US, it is largely
preventable with routine screening.
"We know that screening
will save lives," Dr. Pickhardt says.
Dr. J. Thomas LaMont,
a professor of medicine at Harvard Medical School and co-author
of an accompanying editorial, says "the importance of this study
is that it offers patients another screening method instead
of [traditional] colonoscopy."
Dr. LaMont believes
this new screening technique will encourage more people to get
screened. The main stumbling block to using virtual colonoscopy
now is that it is not covered by insurance, he notes.
Right now only half
of Americans who should undergo screening for colorectal cancer
are pursuing this test, Dr. LaMont says.
"We should do a lot
better, because this is a disease that, if found early, is completely
curable," he says.
Experts
Say Know All of the Facts
A statement released
by Dr. Douglas K. Rex, president of the American College of
Gastroenterology, states, "Considering all available literature,
conventional colonoscopy as currently performed remains the
clear gold standard for the diagnosis of colorectal cancer and
adenomas.
"Patients should be
aware that in this study of virtual colonoscopy and in some
others, they are more likely to experience significant discomfort
with virtual colonoscopy than they are with conventional colonoscopy,"
Dr. Rex advises.
Dr. Rex adds, "Thus
virtual colonoscopy is a diagnosis-only test, whereas conventional
colonoscopy remains the only strategy that allows both diagnosis
and treatment in a single session."
Always consult your
physician for more information.
Online
Resources
(Our Organization
is not responsible for the content of Internet sites.)
American
Cancer Society
American
Gastroenterological Association
Centers
for Disease Control and Prevention (CDC)
National
Institutes of Health (NIH)
US
Department of Heath and Human Services
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January 2004
Virtual
Colonoscopy Finds Colorectal Cancer, Study Shows
Study
Use of 3-D Imaging Aids Accuracy
Experts
Say Know All of the Facts
Vitamin
C May Ward Off Stroke
Online
Resources
Vitamin
C May Ward Off Stroke
People who eat a diet
rich in vitamin C may be at lower risk of suffering strokes,
and smokers who do so may benefit the most, according to a report
in the medical journal Neurology.
A new Dutch study
finds people with the lowest amount of vitamin C in their diets
were 30 percent more likely to have a stroke than people with
the highest amount of it.
People with the highest
amount of vitamin C in their diets consumed more than 133 milligrams
(mg) of vitamin C per day. People with the lowest amount in
their diets got less than 95 mg per day. The recommended daily
amount is 60 mg a day.
Rich sources of vitamin
C include oranges and other citrus fruits, strawberries, red
and green peppers, broccoli, and brussels sprouts.
Smokers with diets
high in vitamin C were more than 70 percent less likely to have
a stroke than smokers with diets low in vitamin C.
Antioxidants such
as vitamin C may protect cells from oxidative stress, which
plays a role in stroke, the researchers say.
"The lower third will
have a higher risk of stroke and those with higher intake will
be at lower risk," says study author Dr. Monique Breteler of
Erasmus Medical Center in Rotterdam. "Vitamins don't react so
differently within populations - so this fits for general populations."
The research "confirms
that the healthy diet is good for you, one that is rich in antioxidants
and vegetables, as we have seen over the last several years,"
she adds.
Researchers studied
5,197 people aged 55 and older living in Rotterdam, all of the
whom had no cognitive problems, were living independently, and
had never had a stroke.
Participants were
then tracked for an average of 6.4 years, and during that time,
253 of them suffered strokes.
"This is not an excuse
to continue smoking. There is more than enough medical evidence
to show that smoking is extremely bad for you," Breteler cautions.
"The effects of anti-oxidation are more than outweighed by other
factors."
Dr. Philip B. Gorelick,
head of the cerebrovascular disease and neurological critical
care department at Rush University Medical Center in Chicago,
says, "I think it's important for the public to keep hearing
the message about our diet and reducing stroke risk, and this
study shows this quite very nicely."
This study appears to
confirm similar findings from a 2002 Finnish study, which showed
a relationship between low vitamin C levels and an increased
risk of stroke. The study of 2,419 men between the ages of 42
and 60 also showed a relationship between high levels of vitamin
C and reduced stroke risk, especially in overweight and hypertensive
men.
One possible explanation
is that vitamin C enhances endothelial function, which lowers
the likelihood of artery blockages and lowers blood pressure.
But the link could
also simply be that people who take vitamin supplements or eat
vitamin-rich fruits and vegetables may be more health-conscious
than those who do not.
Study authors caution
that vitamin C alone may not be responsible for the results
of the study.
Always consult your
physician for more information.
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