Virtual Colonoscopy as Effective as Standard Test, Study Finds
A "virtual colonoscopy," which uses X-ray images and computer software to create three-dimensional images of the colon, is equally effective at detecting precancerous polyps as the "invasive" conventional exam, which uses a small camera that is snaked through the colon, according to a study to be published in Thursday's issue of the New England Journal of Medicine, the Washington Post reports (Stein, Washington Post, 12/2). The study was presented Monday at the annual meeting of the Radiological Society of North America in Chicago. Researchers led by Dr. Perry Pickhardt, an associate professor of radiology at the University of Wisconsin Medical School, gave 1,233 asymptomatic people ages 50 to 79 a virtual colonoscopy followed immediately by a traditional colonoscopy for comparison (Kolata, New York Times, 12/2). Researchers found that the virtual colonoscopy detected 93.8% of polyps at least 10 millimeters in diameter -- the size most doctors believe to dangerous -- while the traditional colonoscopy found 87.5% of such growths (Forelle, Wall Street Journal, 12/2). The virtual colonoscopy found 93.9% of polyps at least eight millimeters in diameter and 88.7% of polyps at least six millimeters in diameter, while the traditional colonoscopy found 91.5% and 92.3%, respectively, of such growths (Pickhardt et al., New England Journal of Medicine, 12/1). The virtual colonoscopy also found two cancerous tumors among the patients, while the standard exam missed one of them, the Boston Globe reports. In addition, the virtual colonoscopy found five cancers outside the colon, as well as several problems in blood vessels, gallbladders and kidneys (Mishra, Boston Globe, 12/2).
According to the study, 54% of patients said that the standard colonoscopy was more uncomfortable than the virtual test, about 38% said that the virtual test was more uncomfortable and about 8% were undecided. However, nearly 70% of the patients said that the virtual colonoscopy was more convenient because they did not have to be sedated (New York Times, 12/2). Both the virtual and standard colonoscopy exams require a 24-hour colon cleansing, which many patients "find the most objectionable part of the procedure," the Los Angeles Times reports. However, the virtual exam "minimizes" the fear of having camera snaked through the intestines, a "psychological barrier that prevents a majority of Americans from undergoing screening for colorectal cancer," according to the Los Angeles Times (Maugh, Los Angeles Times, 12/2). Colon cancer, which is the second leading cause of cancer death, strikes about 105,500 U.S. residents per year and kills more than 57,000 U.S. residents per year, the Post reports. However, only about a third of those who should receive some sort of colon screening do so, according to the Post.
"Colon cancer is a largely preventable disease -- we just have to get people through the door to get screened," Pickhardt said, adding that the virtual colonoscopy "could help do that. ... We could save countless lives." In an accompanying editorial, J. Thomas Lamont, chief of gastroenterology at Beth Israel Deaconess Medical Center, said that the study's findings are "impressive" and that the virtual colonoscopy would be "ready for prime-time" if the results of the study are confirmed (Washington Post, 12/2). However, some medical experts contend that there are problems with the virtual colonoscopy because polyps of any size can be and often are removed during a traditional colonoscopy, the New York Times reports. A polyp size limit has to be set to determine if patients with polyps discovered during a virtual colonoscopy should undergo a traditional colonoscopy to have the polyps removed (New York Times, 12/2). Robert Smith, director of cancer screenings for the American Cancer Society, said that setting a polyp size limit will be "tricky," the Journal reports. He added that if doctors decide to excise smaller polyps, the cost savings from the virtual exam -- which costs between $500 and $1,000, compared with $1,000 to $2,000 for the traditional colonoscopy -- would "quickly erode," according to the Journal (Wall Street Journal, 12/2). Dr. Herman Kattlove of the ACS said that the society will continue to recommend the traditional colonoscopy until the results of the study can be confirmed by radiologists at community hospitals (Los Angeles Times, 12/2). The study is available online. Note: You must have Adobe Acrobat Reader to view the study.
The following broadcast programs reported on the virtual colonoscopy:
- CBS' "Evening News": The segment includes comments from Pickhardt (Kaledin, "Evening News," CBS, 12/1). The full segment is available online in RealPlayer.
- NBC's "Nightly News": The segment includes comments from Pickhardt (Bazell, "Nightly News," NBC, 12/1). The full segment is available online in Windows Media.