CT Colonography vs Colonoscopy

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• CT Colonography vs Colonoscopy
• for 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 3571403-1412
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Background
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Ct Colonography
http//www.radiologyinfo.org/en/photocat/photos_pc
.cfm?imagevcoloMovie.jpgpgct_colo
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• Colorectal cancer
• A major cause of cancer-related mortality in the
  US (55,000 deaths/yr)
• Preventable by detection and removal of its
  precursor
• advanced colonic adenoma

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Colonic adenoma progression
Advance colonic adenomas gt10mm
Small adenomas lt 5mm
dysplasia
Cancer
10 yrs
Most likely Hyperplastic 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 preventive strategy of
  CRC by AGS
• CT colonography (CTC) is a non-invasive promising
  alternative screening method
• Most trials examining CTC had failed to show
  comparative sensitivity/specificity to OC.

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Methods
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• Study design Single center, non randomize
  clinical trial comparing CTC vs 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
  gt 6mm) by CTC were given the option of
  surveillance with CTC or removal of the polyp by
  OC.
• In the OC group, All polyps/masses found were
  removed, regardless of size or significance.
• All removed masses were evaluated for location
  relative to the splenic flexure, morphologic
  characteristics, and histology.

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• Screening Methods
• Lesions were divided into two categories
• Polyps
• Large gt 10mm
• Small 6-9 mm
• Diminutive 5mm or less
• Invasive mass

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• Statistics
• A positive test was defined as detection of
  polyps of any size in the OC group and polyps of
  gt6mm in the CTC group.
• The two tests were compared using students
  T-test and Chi square analyses

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Results
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Optical colonoscopy
A sessile polyp An adenomatous polyp
http//www.murrasaca.com/colonoscopy.htm
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3120 Patients were enrolled in CTC screening
2716 (87.1) had negative findings
404 (12.9) had positive findings
Routine follow-up in 5 yrs
158 (5.1) chose ongoing imaging surveillance
246 (7.9) underwent OC with polypectomy
With 193 polyps
With 394 polyps (gt6mm)
227 adenomas
14 Cancers
153 non-neoplastic tumors
123 Advanced neoplastic lesions
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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 advance neoplasia (p 0.81)
• CTC had an advantage of safety, no requirement
  for sedation, and detecting extra-colonic
  abnormalities
• There were larger number of polypectomies in the
  OC (2434) vs. in the CTC (561) while total
  advance neoplasias were similar in both (121/2434
  vs 123/561)

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• PPV for advance neoplasia
• TP / TPFP
• CTC 123 / 561
• OC 121 / 2434

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Discussion
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Study Strength

• Large sample size, similar baseline
  characteristics
• Relevant exclusion criteria
• Detailed pathological characterization of tissues
  in addition to imaging to establish comparative
  detection
• Could have significant clinical and economical
  impact on current practice of colon CA screening

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Weakness

• Non blinded/non-randomized (selection bias)
• single Center
• Technical advancement may vary between centers
  for effective CTC screening
• True negatives in pts with lesions lt 5mm in the
  CTC group is not determined

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Clinical Practice Relevance

• Offers CTC as a non-invasive alternative to OC
  for comparative detection of colonic neoplasias
• Eliminates the need for a large number of
  unnecessary colonoscopies and polypectomies
• Due to variability in technical resources CTC may
  not yet be a potential replacement for OC in many
  practice settings

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Thank you