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

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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

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

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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.