CT Colonography vs Colonoscopy
for the Detection of AdvancedNeoplasia
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., MarkReichelderfer, M.D., Richard H. Hsu, M.D., and Patrick R. Pfau, M.D.
NEJM Oct 4, 2007 Volume 357:1403-1412
Background
Ct Colonography
http://www.radiologyinfo.org/en/photocat/photos_pc.cfm?image=vcoloMovie.jpg&pg=ct_colo
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
Colonic adenoma progression
Small adenomas< 5mm
dysplasia
Advance colonicadenomas>10mm
Cancer
10 yrs
Most likelyHyperplastic
Usually do notprogress to cancer
Study Objective
–Optical colonoscopy (OC) is currentlythe 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.
Methods
Study design: Single center, nonrandomize clinical trial comparing CTCvs OC screening in a 25 month period
Study population: 6283 pt referred byprimary care providers.
•3120 CTC screening
•3163 OC screening
Inclusion/Exclusion criteria
•Inclusion
–Asymptomatic and average risk forcolorectal CA
•Exclusion
–Prior polyp surveillance
–History of bowel disorder (IBD,polyposis syndromes, hereditary nonpolyposis colorectal cancer syndrome)
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.
Screening Methods
•Lesions were divided into two categories:
–Polyps
•Large: > 10mm
•Small: 6-9 mm
•Diminutive: 5mm or less
–Invasive mass
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 usingstudent’s T-test and Chi squareanalyses
Results
Optical colonoscopy
http://www.murrasaca.com/colonoscopy.htm
A sessile polyp
An adenomatouspolyp
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 withpolypectomy
With 193 polyps
123 Advanced neoplastic lesions
14 Cancers
153 non-neoplastic tumors
More Information
Summary of Results
•Both CTC and OC had comparativediagnostic 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)
PPV for advance neoplasia
•TP / TP+FP
–CTC123 / 561
–OC 121 / 2434
Discussion
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
Weakness
•Non blinded/non-randomized (selectionbias)
•single Center
•Technical advancement may vary betweencenters for effective CTC screening
•True negatives in pts with lesions < 5mm inthe CTC group is not determined
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 andpolypectomies
•Due to variability in technical resourcesCTC may not yet be a potential replacementfor OC in many practice settings
Thank you