Electronically Cleansed Colon Screening

Colorectal cancer CT colonography system requires no laxatives

/ Author:  / Reviewed by: Chris Galloway, M.D.

(RxWiki News) If you've ever had a colonoscopy, you know about the colon emptying routine. It can be unpleasant. A new screening technology eliminates the need for all that eliminating.

Virtual colon exams or colonoscopy that requires no laxative preparation are just as effective as standard colonoscopy at detecting high-risk growths (polyps) that can turn into cancer.  

The new system virtually cleanses and examines the colon.

"Find out when you should begin having colorectal cancer screening."

Researchers from Massachusetts General Hospital (MGH) have found that the computer-aided systems were able to identify about 90 percent of 10 mm (.39 in) or larger common polyps (adenomas).

"While we know that colon screening can save lives, not enough people participate, in part because of the discomfort of the required laxative preparation," says study leader, Michael Zalis, MD, director of CT Colonography at MGH.

"In our study, the laxative-free form of CT colonography performed well enough that it might someday become an option for screening, which we hope would increase patient participation."

Traditional colonoscopies use fiber optic tubes fitted with a light and camera to examine the inside surface of the colon. Patients need to take some form of laxative to clear the colon for best viewing, and they must be sedated during the procedure.

CT colonography uses CT scanning imaging technology and has some advantages, including no need for sedation. However standard CT colonography still requires the laxative preparation.

The new system doesn't require any laxative. Instead, patients are asked to eat a low-fiber diet for two days prior to the screening, and they take a contrast agent which indicates fecal matter in the colon.

A software program developed by MGH "virtually cleanses" the fecal matter to look for polyps (adenomas) that could develop into cancer.

To test the system, researchers worked with 604 patients who were scheduled for screening colonoscopy between 2005 and 2010.

The laxative-free CT colonography was performed five weeks before the traditional optical colonoscopies. Gastroenterologists performing the colonoscopies weren't told about the polyps located in the first procedure. 

Results of the colonography were analyzed by three MGH radiologists trained in interpreting both methods but unaware of the results of the colonoscopy. Patients also completed written surveys about their experiences.

Researchers found the laxative-free method was just as good as colonoscopies at picking up 10 mm or larger polyps. The technology wasn't as effective in detecting smaller polyps, but this size growth is less likely to contain cellular changes common with the development of cancer.

The majority of participants (62 percent) preferred the laxative-free method over the traditional method.

"If we can validate that this form of CT colonography performs reasonably well for screening and is easier for patients, it could have a significant impact on reducing the incidence of colon cancer and related cancer deaths,"  said Dr. Zalis, who is also associate professor of radiology at Harvard Medical School.

This research was published May 14, 2012 in the Annals of Internal Medicine.

GE Healthcare and the American Cancer Society supported this research. Author conflict of interest disclosures were not publicly available.

Reviewed by: 
Review Date: 
May 14, 2012
Last Updated:
July 9, 2012