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DDW 2016: Endoscopist’s Knowledge of Positive Cologuard Test Improves Colonoscopy Performance

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Key Points

  • Unblinded endoscopists found polyps or hemorrhagic lesions 83% of the time and precancerous polyps in 70% of patients, compared to 68% and 53% of blinded endoscopists, respectively.
  • Unblinded endoscopists spent 46% more time and found twice as many polyps per colonoscopy.

An endoscopist's knowledge of a positive Cologuard test improves colonoscopy performance, according to a poster presentation by Johnson et al at Digestive Disease Week (DDW) 2016 (Abstract Su1044).

Cologuard is an at-home, stool-DNA colorectal cancer screening test that has been approved by the U.S. Food and Drug Administration. This test, available by prescription only, is reimbursed by Medicare and covered by an increasing number of commercial health-care plans.

Study Findings

Researchers from Mayo Clinic compared results of colonoscopies following a positive result from Cologuard (unblinded) with colonoscopies performed by those who were not aware of the Cologuard result (blinded). Unblinded endoscopists found polyps or hemorrhagic lesions 83% of the time and precancerous polyps in 70% of patients, compared to 68% and 53% of blinded endoscopists, respectively.

The study also showed that unblinded endoscopists spent 46% more time and found twice as many polyps per colonoscopy.

“Endoscopist knowledge of a positive Cologuard result appears to enhance colonoscopy quality, based on observed differences in number of detected lesions, total adenomas, detection of inconspicuous or flat lesions, and withdrawal times,” said David Johnson, MD, a gastroenterologist at Mayo Clinic's Rochester campus. “This increase in yield could translate into more true-positive and fewer false-negative results than estimated from blinded preapproval studies.”

The blinded group included a portion of the Cologuard-positive patients who participated in the DeeP-C clinical trial. Its results were published by Imperiale et al in the April 2014 issue of The New England Journal of Medicine. The DeeP-C study evaluated Cologuard's performance in nearly 10,000 patients. Cologuard was found to be 92% sensitive in detecting colorectal cancer with 87% specificity.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.


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