AIM: Is CTC given an equal chance for colon cancer screening?

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Unlike other colorectal cancer screening tests that are currently recommended by the U.S. Preventive Services Task Force (USPSTF) and the Centers for Medicare & Medicaid Services (CMS), CT colonography (CTC) screening appears to be held to a higher standard, according to a perspective published in the Feb. 3 edition of the Annals of Internal Medicine.

Samita Garg, MD, and Dennis Ahnen, MD, of the Denver Veterans Affairs Medical Center and the University of Colorado Denver School of Medicine, said that the recent guidelines for colorectal cancer screening have varied in their conclusions on whether CTC is an acceptable screening option. As a result, the CMS has decided against covering CTC screening for patients.

Concerns regarding CTC for colon cancer screening from the CMS include:

  • Radiation exposure;
  • False-negative rates for small polyps;
  • The discovery of extracolonic findings;
  • Variability in performance;
  • A lack of targeted studies;
  • A higher adenoma rate in the Medicare-eligible age group; and,
  • An absence of evidence that covering CTC would increase overall screening rates.

Despite the inconclusive findings of recent studies pertaining to CTC for the screening of colorectal cancer, the authors noted that the rationale against recommending or covering CTC raises concerns, as similar results to CTC have been found for other recommended and covered colon cancer screening tests.

The perspective noted that both the USPSTF and the CMS agree that CTC compares favorably with colonoscopy for the detection of cancer or polyps greater than 9 mm in diameter and that this screening method has been associated with lower rates of complications than colonoscopy. 

However, current data regarding the relative patient acceptability and cost-effectiveness of CTC are conflicting, which led the USPSTF and CMS not to approve CTC, according to Garg and Ahnen. This decision “seems to set a new standard for review of colorectal cancer screening tests,” they wrote.

“Changing the standards for new tests when current screening tests are thought to be effective may be appropriate and indeed laudable,” wrote the authors, “but, we should recognize this and make the new standards clear to those who may wish to develop new colorectal cancer screening tests.”