As published by the Wall Street Journal

By Charles Forelle

Now you have one less excuse to avoid getting a colonoscopy. New type of “virtual colonoscopy” can reveal potentially cancerous growths at least as well as the famously uncomfortable traditional colonoscopy, according to a new study, a finding that could help bring the method into the medical mainstream and lead many more people to get screened for colon cancer.

Colorectal cancer, a slow-developing disease that kills more than 50,000 people each year in the U.S., is highly treatable if caught early. But the traditional screening method, which involves inserting a camera through the rectum, is so unpleasant that many people avoid getting it. Studies suggest that only about one-third of those for whom screening is recommended actually get tested. Doctors hope the virtual scan could encourage more people to get screened and reduce some of the burden on busy hospitals, where the wait for a traditional colonoscopy can stretch to many months.

”This is a step in the right direction,” says Bernard Levin, a gastroenterologist and vice president of cancer prevention at the University of Texas MD Anderson Cancer Center. “As a clinician, this makes the job of selling screening – which is not yet as widespread as we would want for people over 50 of average risk – easier.” Dr. Levin wasn’t involved in the study, which is to be published later this week in the New England Journal of Medicine and was presented at a radiology conference yesterday.

But the technology used in the study isn’t the same as that used in hundreds of screening venues around the country that now offer virtual colonoscopies. Most of those centers employ a method that requires radiologists to squint at scores of two-dimensional images of colon sections. Previous studies found that approach to be less effective than the regular colonoscopy, and the American Cancer Society has declined to recommend the virtual approach as a primary screening method. Consequently, though virtual colonoscopies are cheaper than the traditional type – between $500 and $1,000, compared with $1,000 to $2,000 – most insurers won’t pay for them.

In the New England Journal study, researchers at the National Naval Medical Center in Bethesda, Md., availed themselves of cutting-edge, three-dimensional imaging software and advanced scanning equipment and found it to work far better. Only about 50 centers nationwide have the particular three-dimensional technology evaluated in the study, which researchers consider the most precise.

In the study, doctors gave 1,233 asymptomatic men and women at three hospitals a virtual colonoscopy and an optical colonoscopy on the same day and compared how many potentially cancerous growths, or polyps, each method found.

The virtual method picked out polyps 10 millimeters or larger – a common threshold that doctors regard as dangerous – in 93.8% of patients who had such growths, while the optical colonoscopy found them in 87.5% of patients. Similarly close results were found with smaller polyps, but the traditional method a slight edge among the smallest growths.

Perry J. Pickhardt, a radiologist at the University of Wisconsin Medical School and a lead author of the study, stressed that the study was performed with sophisticated scanning equipment and an advanced 3D software rendering tool, made by closely held Viatronix Inc. of Stony Brook, N.Y. “One concern I have is that people may assume that virtual colonoscopy is ready for prime time regardless of your approach,” he said.

Not surprisingly, people in the study preferred the virtual exam by a five to four margin, and generally found it to be more convenient. The virtual trip up and down the colon “was absolutely incredible,” says Frank Rasada, a 69-year-old sales representative from La Quinta, Calif., who had a virtual colonoscopy last week outside the study. “It’s like going through a tunnel.” The procedure cost him $650, but he considered it money well spent. It was less uncomfortable than the two traditional colonoscopies he’s had. (“When it hits a corner, you know,” he says of the colonoscopy scope.)

Still, there are some drawbacks to the virtual approach. Patients still have to prepare for the three-dimensional virtual exam by cleansing the bowel, going on a liquid diet, and drinking a barium solution that “tags” lingering stool deposits. Also, if a potentially cancerous growth, or polyp, turns up on a virtual exam, patients would still need a traditional, optical colonoscopy to remove it.

And the virtual method isn’t appropriate for people who are at high risk for having colorectal cancer, says Joel Bortz, a Palm Desert, Calif., radiologist who performed Mr. Rasada’s procedure.

“If there is known cancer in the family, if there is active bleeding, if there are known polyps from another study, don’t do it,” he says.

Some doctors cautioned that virtual colonoscopy leaves a substantial open question: How big does a polyp identified during such an exam need to be before doctors decide to remove it? Doctors generally believe polyps of less than 10 millimeters aren’t immediately dangerous, although they could later grow. But some advocate removing small polyps anyway during the traditional colonoscopy, because it can be done on the spot.

Robert Smith, an epidemiologist who is director of cancer screening at the American Cancer Society, says virtual colonoscopies will require doctors to set size parameters for polyp removal, which could get tricky. “What do you do about a 9 millimeter lesion?” he asks. If doctors and patients decided to excise smaller growths, he adds, any cost savings from the virtual procedure could quickly erode.