Virtual Colonoscopy Shows Promise
Study Shows It's Less Invasive and Possibly More Effective Than Conventional Screening
"And when the procedure is over, they can drive themselves home because they haven't been sedated."
Both procedures require the same preparations -- avoiding solid food the day before the test and cleansing the bowel with laxatives to remove all fecal matter.
Choi's study, presented Monday before the Radiological Society of North America and published in this week's New England Journal of Medicine, is the first to test 3-D computed tomography as a screening method for colon cancer for average-risk people. But in recent years doctors have taken two-dimensional CT images of the colon, and studies have suggested these virtual 2-D images may be less sensitive at detecting polyps than conventional colonoscopy in a low-risk population.
In fact, an analysis of 16 previous studies presented in October before the American College of Gastroenterology indicated that virtual colonoscopy missed 27% of colorectal lesions that were picked up by conventional colonoscopy.
"Based on that analysis, that means one in five patients had polyps missed with virtual colonoscopy that were picked up with conventional colonoscopy," says Aaron A. Link, MD, of the University of Michigan, who headed that analysis.
"It would be great if these new findings could be replicated because there are many times when virtual colonoscopy is very useful," Link tells WebMD. "It's certainly easier on the patient, and many aren't agreeable to conventional colonoscopy."
Only about 40% of Americans at risk for colon cancer -- the second largest cause of cancer-related death -- get screened because they say colonoscopy is unpleasant. The procedure is recommended for all people after age 50, and earlier for those with a family history of colon cancer or other bowel diseases. Guidelines recommend screening of adults who are at average risk because detection and removal of polyps has been shown to virtually eliminate the risk of colon cancer.
"The goal of screening with virtual colonoscopy is to increase the number of patients that would participate," says Choi.
Still, the newer virtual method can only screen the colon for the presence of polyps. If a polyp is detected, traditional colonoscopy or surgery is needed to remove it.