Virtual Colonoscopy ...safer and cheaper

Apr 24 2007

New technology called "virtual colonoscopy" is promising to offer fewer complications and be more cost-effective than the traditional colonoscopy.

Colonoscopies which are the most accurate test for colorectal cancer detection in current use, involve the insertion of a tube, or "endoscope," through the colon while the patient is sedated.

A small camera visualizes any polyps, which are then snared and removed for microscopic evaluation.

The researchers say by using computed tomography (CT) imaging of the colon, removing polyps smaller than 6 millimeters, which as a rule do little to reduce the risk of colorectal cancer, can be avoided along with the invasive and expensive colonoscopy procedure.

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, says the almost nonexistent risk associated with such small polyps, means 90 percent of people do not need an invasive and expensive colonoscopy to screen for colon cancer.

Dr. Pickhardt says virtual colonoscopy is a very effective way to filter out these people and focus on those who really need the more invasive procedure.

Pickhardt says he is not suggesting that virtual colonoscopies replace traditional optical screening but non-invasive screening might increase the number of people who would then decide to undergo screening.

According to the American Cancer Society (ACS), colorectal cancers are the third most common cancers in the United States among both men and women and 112,000 Americans will be diagnosed with colon cancer this year; of those 52,000 will die.

At an increased risk for colon or rectal cancer are those over the age of 50, smokers, African-Americans, Jews of Eastern European descent, those with a personal or family history of the disease, or those with a history of polyps or bowel disease.

If caught early the disease as a rule responds well to treatment.

Virtual colonoscopy is a combination of sophisticated X-rays and CT scans of the abdomen after it has been pumped with air; from this a two and three-dimensional computer model of the gastrointestinal tract is generated, which reveals potential cancerous and precancerous lesions.

When dangerous lesions are identified, a second, more invasive procedure is then required.

The virtual method has the advantage of being faster, involving no sedation, no post-procedure recovery, and no risk of invasive complications such as abdominal bleeding or life-threatening bowel perforation as can happen with colonoscopies.

The ACS says the technology holds great promise but suggests further research is needed before the procedure is widely adopted and advises other screening methods should continue to be used such as 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.

Pickhardt and his colleagues involved 100,000 patients with an average risk for colorectal cancer in their study and found that their model indicated that 2,940 patients would ultimately go on to develop colorectal cancer.

Pickhardt and the team say the high-tech procedure is not yet widely available but they believe CT colonography will be a recommended front-line screening option (alongside optical colonoscopy) within the year; until then in terms of both preventing cancer and minimizing cost, the use of any screening method was better than no screening at all.

The research is published in the current issue of Cancer.