“Virtual colonoscopy” without laxatives may be nearly as effective as colonoscopy

Bloomberg News reports that “Colon cancer screenings that don’t require laxatives are almost as effective as colonoscopies and may encourage more people to be tested,” according to a study published in the Annals of Internal Medicine.

The research “included 605 adults ages 50 to 85 years who were at average to moderate risk for colon cancer.” Participants “first underwent CT-scan colon screenings with contrast and then the more-common optical colonoscopy with laxatives.”

The Los Angeles Times “Science Now” blog reports that “The key to the new procedure is a radioiodine-labeled tagging agent that patients drink in small doses for two days prior to the procedure.”

When “combined with a low-fiber diet, the tagging agent binds to the feces in the bowel.”

Then, “when the CT is performed, technicians can electronically remove feces from the image, allowing doctors a clearer view of the bowel itself.”

The Wall Street Journal “Health Blog” reports that the CT scans correctly identified 91% of participants who had colon polyps that were at least 10mm or larger.

Reuters reports, however, that the investigators found that virtual colonoscopy was not as good as traditional colonoscopy when it came to spotting polyps smaller than one centimeter.

MedPage Today reports, “Because the vast majority of polyps that impact cancer and survival outcomes are 10 mm or larger, the laxative-free method would likely be worthwhile as a way to reach the many adults whose ‘strong aversion’ to laxative bowel preparation stops them from getting screened, the researchers suggested.”

HealthDay points out that “not surprisingly, patients who underwent the laxative-free procedure preferred it.”

WebMD reports, “A Dutch study published in January had similar results.” Investigators “randomly divided people ages 50-75 into two groups: One was invited to have a conventional colonoscopy, the other a laxative-free virtual colonoscopy.” Although “colonoscopy picked up more advanced abnormal growths, a higher percentage of people invited to have CT colonography agreed to be screened.”

Meanwhile, the Boston Globe “Daily Dose” blog reports that approximately “one in five patients must undergo a standard colonoscopy after the imaging procedure to have suspicious looking polyps snipped off and biopsied.”

Additionally, “the CT scan…delivers a dose of radiation that – while only one-fifth of the dose of an abdominal CT scan – was significant enough to raise the flags of the US Preventive Services Task Force.”

About four years ago, “the government advisory group decided in 2008 not to recommend the use of virtual colonoscopy, saying that evidence wasn’t sufficient enough to prove that the test’s benefits outweighed its harms, which include a dose of radiation with every screening test.”

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