Sept. 17, 2008 — Virtual colonoscopy — colon cancer screening using CT filters — finds 90% of expansive, precancerous polyps.

The finding comes from 15 scholastic and community restorative centers that performed both virtual colonoscopy (CT colonography) and conventional colonoscopy on 2,600 patients matured 50 and more seasoned.

The think about “validates” new rules endorsing virtual colonoscopy as a colon cancer screening alternative, says ponder pioneer C. Daniel Johnson, MD, professor of radiology at the Mayo Clinic in Scottsdale, Ariz.

“Up to presently, there has been conflicting data on how good this test would be,” Johnson tells WebMD. “Typically the largest consider to date on CT colonography. The performance data appears the affectability is very similar to that quoted for colonoscopy.”

The think about showed that virtual colonoscopy was able to detect 90% of polyps 10 millimeters or more in diameter. That’s the same exactness detailed for colonoscopy itself in other thinks about.

Colonoscopy is, however, able to identify much smaller polyps. As the estimate of polyps gets littler, so does the ability of virtual colonoscopy to distinguish them.

Johnson and colleagues found that CT colonography might identify 78% of polyps as small as 6 millimeters in breadth. However the filters caught as it were 65% of polyps 5 millimeters or littler.

“It isn’t clear that taking off little polyps is secure,” notes a news release from the American Gastroenterological Affiliation.

Polyps of 10 millimeters or more progress to cancer at a rate of 1% per year. Polyps half that size should not advance to cancer any faster, but the rate at which such polyps advance isn’t known.

Johnson and colleagues note that less than 2% of polyps littler than 5 millimeters have features that suggest they are precancerous.

Virtual Colonoscopy, Real Bowel Prep

A downside of virtual colonoscopy is that it requires the same bowel prep (cleansing of the bowels) as a genuine colonoscopy.

Patients’ greatest complaint approximately colonoscopy is the prep, not the strategy itself, says inside medication master Robert Fletcher, MD, teacher emeritus at Harvard College.

“Nobody ever said the prep was easy, and it is fair the same for the CT colonography because it is for colonoscopy,” Fletcher tells WebMD. “And if the filter finds something within the colon, which it does approximately 17% of the time, you’ve got to turn right around and get prepped once more and have a colonoscopy, unless it can be organized the same day.”

Johnson says that centers performing CT colonography should be prepared to offer same-day colonoscopy for patients who need it. Fletcher says it’s imperative for patients to ask approximately this some time recently choosing virtual colonoscopy as a screening alternative.

Virtual colonoscopy features a 14% false-positive rate. That’s not terrible, considering it’s a screening test outlined to catch as numerous polyps as conceivable. But patients who get a false alarm will have to be compelled to undergo an superfluous colonoscopy.

Of more prominent concern to Fletcher is the fact that CT checks see more of the body than fair the bowel. For 16% of patients within the Johnson think about, the filters detected non-bowel problems serious enough for further tests or critical care.

“It’s not unimportant for your specialist to tell you, ‘I found something in your kidney or on your adrenal gland,'” Fletcher says. “The chances of helping individuals are beautiful low for those things outside the colon. And after that there is the stress, the bother, of additional tests and of finding extra bad things you never knew around but cannot be changed now simply know.”

Johnson encompasses a totally different view of the issue.

“Colonoscopy cannot see exterior the colon. CT colonography does,” he says. “So there is an opportunity among patients age 50 and more seasoned to be able to hunt for other variations from the norm that will be asymptomatic but may cause harm within the future. We are able to explore for abdominal aortic aneurysms and tumors in other body parts.”

Is Virtual Colonoscopy for You?

This year, the American Cancer Society, the American College of Radiology, and the U.S. Multi-Society Errand Constrain on Colorectal Cancer added CT colonography to the list of colon cancer screening options.

The American Gastroenterological Affiliation notes that as it were half of people get recommended colon cancer screening, and that virtual colonoscopy might make strides this too bad measurement.

But GI specialists aren’t yet prepared to grasp CT colonography, says David A. Margolin, MD, executive of colorectal surgery investigate at the Ochsner Clinic Establishment in Unused Orleans.

“CT colonography will, in the future, play a part in colon cancer screening,” Margolin tells WebMD. “At centers of brilliance, at a very few centers where the quality of software and the CT build and fabulous radiologist training all meet, it is valuable. But in case you anticipate these kinds of comes about at every community hospital, you won’t get it.”

Johnson admits that radiologists require specialized preparing and experience some time recently they’re prepared to perform screening CT colonography. But he says that kind of training is promptly accessible.

And Johnson notes that the consider deliberately included community clinics and a wide run of different CT equipment and program to simulate what might happen when virtual colonoscopy gets to be more common.

“We spend a parcel of time training and testing our CT colonography readers. It does require a special ability set,” he says. “These are great questions for patients to inquire their radiologist: How many CT colonographies have you studied? How much preparing have you had? Radiologists who profit themselves of this preparing can get the same results we report.”

The Johnson think about — and Fletcher’s editorial comments — show up within the Sept. 18 issue of TheNew Britain Journal of Pharmaceutical.