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CT Colonography vs Colonoscopyfor the Detection of Advanced

Neoplasia David H. Kim, M.D., Perry J. Pickhardt, M.D., Andrew J. Taylor, M.D., Winifred K. Leung,

M.D., Thomas C. Winter, M.D., J. Louis Hinshaw, M.D., Deepak V. Gopal, M.D., Mark Reichelderfer, M.D., Richard H. Hsu, M.D., and Patrick R. Pfau, M.D.

NEJM Oct 4, 2007 Volume 357:1403-1412


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Background


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Ct Colonography

http://www.radiologyinfo.org/en/photocat/photos_pc.cfm?image=vcoloMovie.jpg&pg=ct_colo
http://www.radiologyinfo.org/en/photocat/photos_pc.cfm?image=vcoloMovie.jpg&pg=ct_colo


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Colorectal cancer:

A major cause of cancer-relatedmortality in the US (55,000 deaths/yr)

Preventable by detection and removal ofits precursor:

advanced colonic adenoma


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Colonic adenoma progression

Small adenomas< 5mm dysplasia

Advance colonicadenomas>10mm Cancer

10 yrs

Most likelyHyperplastic

Usually do not progress to cancer


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Study Objective


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Optical colonoscopy (OC) is currently

the preferred screening and preventivestrategy of CRC by AGS

CT colonography (CTC) is a non-invasive promising alternative screeningmethod

Most trials examining CTC had failed toshow comparative sensitivity/specificityto OC.


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Methods


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Study design: Single center, nonrandomize clinical trial comparing CTCvs OC screening in a 25 month period

Study population: 6283 pt referred by primary care providers.

3120 CTC screening 3163 OC screening


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Inclusion/Exclusion criteria Inclusion

Asymptomatic and average risk for

colorectal CA Exclusion

Prior polyp surveillance

History of bowel disorder (IBD, polyposis syndromes, hereditary non polyposis colorectal cancer syndrome)


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Screening Methods

Pt identified with advanced neoplasm(mass/polyps > 6mm) by CTC were given theoption of surveillance with CTC or removal ofthe polyp by OC.

In the OC group, All polyps/masses found wereremoved, regardless of size or significance.

All removed masses were evaluated for locationrelative to the splenic flexure, morphologiccharacteristics, and histology.


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Screening Methods

Lesions were divided into two categories: Polyps

Large: > 10mm Small: 6-9 mm Diminutive: 5mm or less

Invasive mass


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Statistics

A positive test was defined as detectionof polyps of any size in the OC groupand polyps of >6mm in the CTC group.

The two tests were compared usingstudents T -test and Chi squareanalyses


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Results


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3120 Patients were enrolled inCTC screening

Routine follow-up in 5 yrs

2716 (87.1%) had negativefindings

404 (12.9%) had positivefindings

With 394 polyps (>6mm)

158 (5.1%) chose ongoingimaging surveillance

227 adenomas

246 (7.9%) underwent OC with polypectomy

With 193 polyps

123 Advanced neoplastic lesions

14 Cancers 153 non-neoplastic tumors


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More Information


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Summary of Results Both CTC and OC had comparative

diagnostic yield for both types of advanceneoplasia (p= 0.81)

CTC had an advantage of safety, norequirement for sedation, and detectingextra-colonic abnormalities

There were larger number of polypectomiesin the OC (2434) vs. in the CTC (561) whiletotal advance neoplasias were similar in both

(121/2434 vs 123/561)


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PPV for advance neoplasia

TP / TP+FP

CTC 123 / 561

OC 121 / 2434


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Discussion


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Study Strength

Large sample size, similar baselinecharacteristics

Relevant exclusion criteria

Detailed pathological characterization oftissues in addition to imaging to establishcomparative detection

Could have significant clinical andeconomical impact on current practice ofcolon CA screening


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Weakness Non blinded/non-randomized (selection

bias)

single Center Technical advancement may vary betweencenters for effective CTC screening

True negatives in pts with lesions < 5mm inthe CTC group is not determined


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Clinical Practice Relevance

Offers CTC as a non-invasive alternative toOC for comparative detection of colonicneoplasias

Eliminates the need for a large number ofunnecessary colonoscopies and

polypectomies

Due to variability in technical resourcesCTC may not yet be a potential replacementfor OC in many practice settings


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Thank you

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