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March 1, 2005 • Volume 2 / Number 9 E-Mail This Document  |  Download PDF  |  Bulletin Archive/Search  |  Subscribe

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Community UpdateCommunity Update

ACRIN Trial May Reveal a Definitive Role for Virtual Colonoscopy

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Concurrent with the sixth annual National Colorectal Cancer Awareness Month in March, the American College of Radiology Imaging Network (ACRIN), a cooperative group funded by NCI, is launching a clinical trial to test the efficacy of computerized tomographic colonography (CTC), or virtual colonoscopy, as a screening tool for detection of colorectal cancer (CRC) at 15 centers across the United States. The National CT Colonography Trial is being led by principal investigator Dr. C. Daniel Johnson of the Mayo Clinic.

The slow, progressive nature of CRC permits detection and treatment of precancerous and localized cancers. Therefore, an enormous opportunity exists to save lives with early detection. Currently accepted CRC screening tools have limitations including poor sensitivity and specificity performance, patient risk, and compliance barriers. "Our goal is to validate a more acceptable and high-performance examination that will translate into higher patient compliance, more patients undergoing the screening exam, and consequently reducing overall colon cancer mortality," says Dr. Johnson.

While CTC is now technically feasible, there is conflicting evidence about its role compared with colonoscopy for CRC screening. Designed to assess CTC's performance versus the "gold standard" of colonoscopy and to address other pertinent CTC questions, trial data are expected to provide a balanced appraisal of the value and practicality of this promising screening tool.

The aims of the study address important clinical applications. These include:

  • Assess the sensitivity and specificity of CTC to detect polyps or cancers of at least 1 centimeter, using colonoscopy as the reference standard.
  • Evaluate inter-observer variability including any benefits of either a primary 3D read or an independent second interpretation.
  • Describe the effects of different colon preparations on the accuracy of CTC.
  • Measure patient acceptance of CTC as compared with colonoscopy.
  • Estimate the accuracy of CTC to detect flat lesions and describe their various morphological features, distribution, and frequency.
  • Report the prevalence and clinical significance of extra-colonic abnormalities detected by CTC.
  • Assess differences in the various CTC software platforms by evaluating user preferences and performance differences.
  • Develop a database of CTC case material for future studies including data appropriate for computer-aided detection development.
  • Assess the cost-effectiveness of CTC as compared with other CRC screening tests.

For more information about the National CT Colonography Trial including a protocol summary and list of participating sites, visit

The American Cancer Society has officially endorsed the trial to assist with patient recruitment efforts.