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A methylene blue dye pill sheds light on hard-to-see polyps


 

A methylene blue dye pill increases the adenoma detection rate in patients undergoing colonoscopy screenings.

“An oral, delayed-release, methylene blue tablet taken during the standard bowel preparation for colonoscopy has the potential to increase the adenoma detection rate and could assist in the early detection and prevention of colorectal cancer,” according to Michael B. Wallace, MD, professor of medicine and director of digestive disease research at the Mayo Clinic in Jacksonville, Fla.

“The number of polyps that providers find during a screening colonoscopy and remove is referred to as the adenoma detection rate. This is the most widely accepted national benchmark on quality for screening colonoscopy,” Dr. Wallace said in a media briefing in advance of the annual Digestive Disease Week®.

Dr. Wallace pointed out that missed adenomas tend to go on and develop into cancer.

“The ones that are most frequently missed are typically called ‘flat’ or ‘subtle’ polyps, making them very difficult to identify,” he said. “If they cannot be identified, they cannot be removed.”

The study involved more than 1,200 patients scheduled for colonoscopies at 20 centers around the world. Patients were randomly assigned to receive a full dose of the methylene blue dye, a half dose, or placebo. Patients receiving a half dose were not included in the statistical analysis, but served the purpose of not allowing doctors to know which patients were in the study group. Dr. Wallace noted that the nature of this study made it impossible to perform a truly double-blind study because the blue dye is visible during colonoscopy.

For the patients who took the full dose of methylene blue, the adenoma detection rate increased by nearly 9%, compared with the placebo group, with detection rates of 56.29% and 47.81%, respectively.

“While 9% may not actually seem like a large number, it is actually very clinically significant,” Dr. Wallace said. For every 1% increase in the absolute adenoma detection rate, there was a corresponding 3% decline in the incidence of colorectal cancer and a 5% decline in colorectal cancer deaths.

While the results of this study are overwhelmingly positive, Dr. Wallace pointed out that utilizing blue dye to increase adenoma detection rate is not a new concept, with a number of clinical trials showing its benefit.

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