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
American
Cancer Society
American
Gastroenterological Association
Centers
for Disease Control and Prevention (CDC)
National
Institutes of Health (NIH)
National
Institute of Neurological Disorders and Stroke US
Department of Heath and Human Services
|
January
2004
In
This Issue:
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
Other
Resources:
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a St. John's Mercy Physician
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John's Mercy Center for New Health Options
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John's Mercy Classes and Programs
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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