Colonoscopy Not Recommended for Colorectal Cancer Screening

New guidelines from the Canadian Medical Association suggest that colonoscopies should not be the primary screening tool for low risk adults aged 50 to 74 years.

Instead, this population should be screened every two years using fecal occult blood testing (FOBT) or flexible sigmoidoscopy every 10 years. The report was published in the Canadian Medical Association Journal.

The Canadian Task Force on Preventative Health Care, an independent panel of clinicians and methodologists, gathered to develop new colorectal cancer screening guidelines. The panel reviewed peer reviewed studies published in the database Medline, the Cochrane Library, and Embase between January 1, 2000 and December 8, 2015.

The guidelines call for biweekly screenings for adults aged 50 to 74 years for colorectal cancer with FOBT or flexible sigmoidoscopy every 10 years. The panel described this as a strong recommendation and said there was moderate quality evidence to support it for patients aged 60 to 74 years. For the patients aged 50 to 59 years, it was considered a weak recommendation, but with moderate quality evidence to support it.

Patients 75 years and older were advised not to be screened for colorectal cancer; this was a weak recommendation supported by low quality evidence. This conclusion was reached after examining the life expectancy of the older group as well as the overall randomized controlled trials identified in the systematic review.

Another weak recommendation supported by low quality evidence was to not use colonoscopy as a primary screening test for colorectal cancer.

“Although colonoscopy may offer clinical benefits that are similar to or greater than those associated with flexible sigmoidoscopy, direct evidence of its efficacy in comparison with the other screening tests (in particular fecal immunochemical testing [FIT]) is lacking,” the authors wrote.

The panel believed these guidelines would reduce mortality from colorectal cancer, as the direct harms linked to these screening tests are minimal, they said. Additinoally, program administrators might consider examining the benefits vs. cost implications of the flexible sigmoidoscopy compared to FOBT.

“Although colonoscopy may offer clinical benefits that are similar to or greater than those associated with flexible sigmoidoscopy, direct evidence of its efficacy from randomized controlled trials in comparison to the other screening tests… is presently lacking; however, ongoing clinical trials are working to address this research gap,” Maria Bacchus, chair of the guideline working group, explained in a press release. “Wait lists for colonoscopy remain long in Canada and have increased over the years.”