CT Colonography versus Colonoscopy
for the Detection of Advanced Neoplasia

Important new study confirms the benefits of Virtual Colonoscopy.
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Background
Advanced neoplasia represents the primary target for colorectal-cancer screening and prevention.  We compared the diagnostic yield from parallel computed tomographic colonography (CTC) and optical colonoscopy (OC) screening programs.

Methods
We compared primary CTC screening in 3120 consecutive adults (mean {+SD} age, 57.0+7.2 years) with primary OC screening in 3163 consecutive adults (mean age, 58.1+7.8 years).  The main outcome measures included the detection of advanced neoplasia (advanced adenomas and carcinomas) and the total number of harvested polyps.  Referral for polypectomy during OC was offered for all CTC-detected polyps of at least 6 mm in size.  Patients with one or two small polyps (6 to 9 mm) also were offered the option of CTC surveillance.  During primary OC, nearly all detected polyps were removed, regardless of size, according to established practice guidelines.

Results
During CTC and OC screening, 123 and 121 advanced neoplasms were found, including 14 and 4 invasive cancers, respectively.  The referral rate for OC in the primary CTC screening group was 7.9% (246 of 3120 patients).  Advanced neoplasia was confirmed in the OC group (3.4%), not including 158 patients with 193 unresected CTC-detected polyps of 6 to 9 mm who were undergoing surveillance.  The total numbers of polyps removed in the CTC and OC groups were 561 and 2434, respectively.  There were seven colonic perforations in the OC group and none in the CTC group.

Conclusions
Primary CTC and OC screening strategies resulted in similar detection rates for advanced neoplasia, although the numbers of polypectomies and complications were considerably smaller in the CTC group.  These findings support the use of CTC as a primary screening test before therapeutic OC.

For further information, refer to WWW.NEJM.ORG , October 4, 2007