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Related Article: Editorial, N Engl J Med 2008 :359 ;1285 -1287 .
Colorectal cancer is the third most common cancer and the second leading cause of death from cancer in the United States, with an estimated 154,000 new cases and 52,000 deaths in 2007.1 There is an enormous opportunity to save lives with broadly applied, widely accepted early-detection programs, since the natural history of colorectal cancer permits the recognition and curative treatment of both precursor adenomas and localized cancers. According to data from multiple sources, mortality from colorectal cancer is reduced with regular screening.1 -3 Despite its effectiveness, colorectal-cancer screening remains underused for many reasons, including drawbacks in terms of the performance, comfort, availability, and expense of currently endorsed test options.
Computed tomographic (CT) colonography uses advanced visualization technology that permits a minimally invasive, structural evaluation of the entire colorectum. It has several potential advantages over other screening tests for colorectal cancer, including rapid imaging of the entire colorectum; a relatively noninvasive technique, with no need for sedation; and a low risk of procedure-related complications.4 ,5
The degree to which CT colonography is effective in detecting asymptomatic colorectal lesions remains a controversial topic, perhaps in part because of differences in patient populations, imaging protocols, and radiologists' qualifications in prior studies. The National CT Colonography Trial of the American College of Radiology Imaging Network was designed to assess the accuracy of CT colonography in detecting histologically confirmed, large colorectal adenomas and cancers (≥10 mm in diameter), with optical colonoscopy (the current clinical standard for colorectal cancer screening) and histologic review used as the reference standard.
Methods
A total of 15 clinical sites participated in the study, which complied with the provisions of the Health Insurance Portability and Accountability Act, and approval was obtained from the institutional review board at each site. Participants were recruited from among all asymptomatic patients 50 years of age or older who were scheduled to undergo routine colonoscopy at the participating sites between February 2005 and December 2006. Patients were excluded from the study if they had had melena or hematochezia on more than one occasion in the previous 6 months; if they had lower abdominal pain, inflammatory bowel disease or familial polyposis syndrome, or a serious medical condition associated with an...