Comment

www.thelancet.com/oncology Published online November 15, 2011 DOI:10.1016/S1470-2045(11)70297-2 1

Published OnlineNovember 15, 2011 DOI:10.1016/S1470-2045(11)70297-2

See Online/ArticlesDOI:10.1016/S1470-2045(11)70283-2

Strong evidence in support of CT colonography screeningFindings from the randomised controlled trial reported by Esther M Stoop and colleagues1 in The Lancet Oncology provide important new data for adherence rates and overall programmatic yield for screening with optical colonoscopy and CT colonography. Particularly, results from this trial1 show a signifi cant 55% improvement in screening participation with CT colonography over colonoscopy, which is a crucial component to the overall success of a screening programme. The overall programmatic yield (per invitee) for advanced neoplasia, which represents the optimum target of colorectal screening, was similar for CT colonography and colonoscopy. The somewhat lower yield of advanced neoplasia per patient assessed with CT colonography can be explained by the specifi c trial methods, most notably, the non-cathartic bowel preparation, the primary two-dimensional reading approach, and the diff erent handling of small polyps (6–9 mm). When an approach of cathartic preparation with oral contrast tagging and primary three-dimensional reading is applied, CT colonography is equivalent or slightly better than optical colonoscopy for the detection of advanced neoplasia.2,3 An additional benefi t of cathartic preparation for CT colonography is the ability to do same-day polypectomy, sparing the patient the need for repeat bowel preparation. Although only a small proportion of 6–9 mm adenomas are histologically advanced, lesions of this size were (appropriately) not sent for polypectomy in the colonography group of this trial, further decreasing its overall immediate yield. However, when the analysis of the comparative yield is restricted to cancers and large advanced adenomas, which are vastly more relevant to clinical outcomes than benign sub-centimetre polyps, CT colonography has the edge over colonoscopy. In terms of cancer detection, a meta-analysis4 reported a 100% sensitivity for CT colonography when a cathartic preparation with contrast tagging was used, and a slightly greater overall sensitivity than that with colonoscopy (96·1% vs 94·7%) when all colonography techniques were included.4

The implication that CT colonography would lead to greater participation in colorectal screening over colonoscopy is a crucial finding, since this modality could operate in parallel with existing colon-oscopic screening. Results from previous studies

have collectively shown a definite overall patient preference for screening with CT colonography over colonoscopy.5 Given this fact, it should not be too surprising that this would translate into improved participation in screening. Nonetheless, the trial design of Stoop and colleagues’ study1 provides even more convincing evidence. In terms of the effect of increased adherence for CT colonography on cost-effectiveness, the ramifications are enormous. Although results from various studies have shown that CT colonography is already more cost-effective than colonoscopy when participation rates are assumed to be equal,6 this difference becomes much more pronounced if the expected adherence rates for CT colonography are increased relative to colonoscopy, as shown in the present study.1 Another key point shown both in this study and previously by Kim and colleagues2 is that the percentage of advanced neoplasia relative to all polyps removed is strikingly higher for CT colonography than with colonoscopy, which further enhances the relative cost-effectiveness (and safety) of CT colonography.

The bottom line is quite simple—too many people are dying of a readily preventable disease. The issue with screening for colorectal cancer is not related to test effi cacy per se, but rather to the willingness of patient participation (and study availability). By off ering the additional option of CT colonography for screening, overall patient outcomes will be positively aff ected by the equivalent (or greater) yield for advanced neoplasia coupled with a decrease in complications and costs. Of note, both colonoscopy and CT colonography confer the crucial advantage of cancer prevention through detection (and removal) of advanced adenomas over the cancer detection aspect alone that is provided by current stool-based testing. The additive yields of having both colonoscopy and CT colonography available as primary screening options could have a profound eff ect on the incidence and mortality of colorectal cancer in the future.

Perry J PickhardtGastrointestinal Imaging, School of Medicine and Public Health University of Wisconsin-Madison, Madison, WI, USAppickhardt2@uwhealth.org

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2 www.thelancet.com/oncology Published online November 15, 2011 DOI:10.1016/S1470-2045(11)70297-2

I have been a consultant for Medicsight, Viatronix, and Bracco, and a cofounder of VirtuoCTC.

1 Stoop EM, de Haan MC, de Wijkerslooth TR, et al. Participation and yield of colonoscopy versus non-cathartic CT colonography in population-based screening for colorectal cancer: a randomised controlled trial. Lancet Oncol 2011; published online Nov 15. DOI:10.1016/S1470-2045(11)70283-2.

2 Kim DH, Pickhardt PJ, Taylor AJ, et al. CT colonography versus colonoscopy for the detection of advanced neoplasia. N Engl J Med 2007; 357: 1403–12.

3 Pickhardt PJ, Choi JR, Hwang I, et al. Computed tomographic virtual colonoscopy to screen for colorectal neoplasia in asymptomatic adults. N Engl J Med 2003; 349: 2191–200.

4 Pickhardt PJ, Hassan C, Halligan S, Marmo R. Colorectal cancer: CT colonography and colonoscopy for detection-systematic review and meta-analysis. Radiology 2011; 259: 393–405.

5 Moawad FJ, Maydonovitch CL, Cullen PA, Barlow DS, Jenson DW, Cash BD. CT colonography may improve colorectal cancer screening compliance. AJR Am J Roentgenol 2010; 195: 1118–23.

6 Pickhardt PJ, Hassan C, Laghi A, Zullo A, Kim DH, Morini S. Cost-eff ectiveness of colorectal cancer screening with computed tomography colonography—the impact of not reporting diminutive lesions. Cancer 2007; 109: 2213–21.