New Choice for Colonoscopy on Horizon
< Apr.
25, 2007 > -- A cutting-edge technology
called "virtual colonoscopy" promises fewer complications
and better cost-effectiveness than traditional
colonoscopy, researchers report in the journal Cancer.
These technologies have been compared
before, but the current analysis relies on the notion
that identifying and removing polyps smaller than
6 millimeters (almost one quarter inch) won't
do much to reduce colorectal cancer cases.
The new technique will not replace
traditional colonoscopy.
"Because there's virtually no
risk associated with having such small polyps, 90
percent of folks don't need an invasive and expensive
colonoscopy to screen for colon cancer," explains
lead researcher Dr. Perry J. Pickhardt, an associate
professor in the school of medicine and public health
and radiologist at the University of Wisconsin in
Madison.
"So, here it was easy to show
that virtual colonoscopy is a very effective way
to filter out these people and hone in on those who
really need the more invasive procedure," he says.
Dr. Pickhardt is not suggesting
that virtual colonoscopies replace traditional optical
screening. But non-invasive screening might up the
number of people who decide to undergo screening,
he says.
"We need to encourage more folks
to get screened, period," says Dr. Pickhardt. "We're
not trying to take away from the screening already
in place. It's a personal choice. Some people prefer
the colonoscopy route compared to virtual colonoscopy,
and that's fine. Just so long as you do one or the
other."
The disease is highly treatable
if caught early, however.
Virtual colonoscopy involves a
combination of sophisticated X-rays and computed
tomography (CT) scans of the abdomen after it has
been pumped with air. A two- and three-dimensional
computer model of the gastrointestinal tract is then
generated, potentially revealing cancerous and precancerous
lesions. If dangerous lesions are spotted, a second,
more invasive procedure is required.
Unlike traditional colonoscopy,
the virtual method is faster, involves no sedation,
no post-procedure recovery, and no risk of invasive
complications such as abdominal bleeding or life-threatening
bowel perforation.
However, the American
Cancer Society ( ACS) has
not yet backed this option as a proven screening
method, citing the need for further research.
Instead, the group suggests other
screening methods, including blood stool tests; a
barium enema combined with X-rays; a flexible sigmoidoscopy
(involving the insertion of a two-foot-long optical
tube through the rectum to examine the lower colon);
and traditional optical colonoscopy, which involves
the insertion of a longer lighted tube to examine
the entire colon.
All people over age 50 are encouraged
to undergo a regular colonoscopy once every 10 years,
or either a barium enema or a flexible sigmoidoscopy
(with or without a yearly blood test) once every
five years.
To compare some of these options,
Dr. Pickhardt and his colleagues developed a mathematical
model involving 100,000 patients with an average
risk for colorectal cancer. They noted that 75 percent
of the American population is subject to such risk.
Polyp searches were based on one
of two thresholds: those measuring 6 millimeters
in diameter and up, and lesions of any size.
The model indicated that 2,940
patients would ultimately go on to develop colorectal
cancer.
The simulation also revealed that
flexible sigmoidoscopy screenings reduced the rate
of cancer by just over 31 percent, while traditional
colonoscopy reduced the rate by just over 40 percent.
Virtual colonoscopies were only
slightly less efficient than the traditional method
-- achieving an almost 38 percent reduction when
polyps of all sizes were considered. The prevention
rate dropped slightly, to 36.5 percent, when screenings
focused only on polyps 6 millimeters and up.
Virtual colonoscopy also had the
added benefit of dramatically reducing the need for
unnecessary polyp removal. Nearly 78 percent fewer
patients went on to have an invasive polyp removal
after a virtual screening compared with patients
who underwent a regular colonoscopy.
And when virtual screenings focused
solely on lesions 6 millimeters and up nearly 12,900
additional unwarranted polyp removals were avoided.
However, Dr. Pickhardt noted that
the high-tech procedure is not yet widely available.
"It's definitely ready for primetime,
but people don't have it everywhere yet," he says. "The
technology is getting better and better, and I can
tell you that it will continue to improve. But most
radiology practices aren't going to invest in the
necessary software, because insurances aren't generally
paying for it yet."
The ACS's director
of cancer screening, Robert Smith, said his organization
is taking a wait-and-see approach toward virtual
colonoscopy. However, he believes the technology
holds great promise.
Always consult your physician
for more information.
|
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When malignant cells are found in the colon or
rectum the diagnosis is colorectal cancer, a curable condition.
The colon and the rectum are part of the large
intestine and digestive system. Because colon cancer and rectal
cancers have many features in common, they are sometimes referred
to together as colorectal cancer. Cancerous tumors found in the colon
or rectum also may spread to other parts of the body.
Excluding skin cancers, colorectal cancer is the
third most common cancer in both men and women. It is estimated by
the American Cancer Society that
153,760 colorectal cancer cases are expected in 2007. The number
of deaths due to colorectal cancer has decreased, which is attributed
to increased screening and polyp removal.
The following are the most common symptoms of
colorectal cancer. However, each individual may experience symptoms
differently.
People who have any of the following symptoms
should check with their physicians, especially if they are over 50
years old or have a personal or family history of the disease:
- a change in bowel habits such as
diarrhea, constipation, or narrowing
of the stool that lasts for more
than a few days
- rectal bleeding or blood in the stool
- cramping or gnawing stomach pain
- decreased appetite
vomiting
- weakness and fatigue
- jaundice - yellowing of the skin and eyes
The symptoms of colorectal cancer may resemble
other conditions, such as infections, hemorrhoids, and inflammatory
bowel disease. It is also possible to have colon cancer and not have
any symptoms.
Although the exact cause of colorectal cancer
is not known, it is possible to prevent many colon cancers with the
following:
- diet and exercise - It is important
to manage the risk factors you can
control, such as diet and exercise.
Eating more fruits, vegetables, and
whole grain foods, and avoiding high-fat,
low-fiber foods, plus appropriate
exercise, even small amounts on a
regular basis, can be helpful.
- drug therapy - Some studies have shown that low doses of nonsteroidal
anti-inflammatory drugs (NSAIDs) such as aspirin, and estrogen
replacement therapy for post-menopausal women may reduce the risk
of colorectal cancer. Discuss this with your physician.
- screenings - Perhaps most important to the prevention of colorectal
cancer is having screening tests at appropriate ages. Because some
colorectal cancers cannot be prevented, finding them early is the
best way to improve the chance of successful treatment, and reduce
the number of deaths caused by colorectal cancer.
Always consult your physician for more information. |
