A story on virtual colonoscopy — especially a colonoscopy that projects images on the wall so that the doctor can “walk through” your intestines — makes for a great television news segment because of the colorful, 3-D imagery accompanying flashy computer animations. But what’s missing from the CBS news report (and the accompanying video segment) is any evidence backing up the headline claim that this technology could “detect cancer earlier” or that it will reduce the number of colorectal cancer cases. It doesn’t cite any studies or solicit the opinions of independent experts. Instead, the only source in this piece is the inventor of the technology. There also isn’t any mention of costs or any discussion on the limitations of the procedure.
Let’s face it: nobody looks forward to a trip to the local endoscopy laboratory for colon cancer screening. The bowel prep is unpleasant and the very thought of the procedure, even under sedation, is met with dread by most. And so a technology that would reduce the need for bowel preparation and fasting has obvious appeal. But is the allure of the new technology matched by evidence that it identifies important lesions and saves lives as effectively as the established version? The answer to that question is crucial, and journalists writing on the topic have a duty to try to answer it. They should avoid inappropriate cheerleading that glosses over the outcomes that matter most.
At the moment there are a number of methods that can be used for screening for colon cancer. All have advantages and disadvantages and may be appropriate in select patient populations. Colonoscopy (the physical kind) is the gold standard. Computed Tomography (CT) colonoscopy, the “virtual” alternative, has had the promise of a more exact method of screening since its introduction. But that promise has not been fulfilled yet, and it has not been recommended by medical experts as a standard. Reports covering the merits of a “high-tech” procedure should proceed with caution and clearly explain why the new technology is better than proven therapies and how its usage translates to better health outcomes for patients.
Cost should always be a consideration in a discussion of a new technology. Screening tests are no exception There are approximately 100 million adults in the US over the age of 50 years according to the 2010 census report. That is a lot of screening, and the financial implications can loom very large. Although the cost of the test, in this case virtual colonoscopy, is important, it is only one piece of the equation. The removal of suspicious lesions cannot be done in the virtual world, so suspicious lesions identified virtually would require a physical colonoscopy, adding to the overall cost. According to the Colon Cancer Alliance, a CT colonoscopy costs between $400 – 800. This cost is not covered by Medicare and most commercial insurance companies.
The piece states that virtual colonoscopy helps doctors view the organ in “remarkable detail.” Dr. Arie Kaufman, the only source quoted in the story, talks about how physicians can “view 100 percent of the surface including legions.”
But what is missing is how more detailed imaging translates to better health outcomes. Are there any studies proving the link between virtual colonoscopy and more lives saved? Can virtual colonoscopy detect more abnormal growths than a regular colonoscopy? And what exactly are the benefits for patients if they opt for a virtual colonoscopy instead of the traditional option? In this 2005 study in the journal Radiology, researchers reported that CT colonoscopy helped detect a “substantial number… [of] clinically important extracolonic findings,” but this did not translate to improved health outcomes.
Virtual colonoscopies still require patients to prepare for the exam, which may include drinking plenty of clear liquids, taking laxatives and swallowing foul-tasting oral solutions. The procedure also entails the insertion of a rectal tube and the pumping of air into the rectum.
Furthermore, virtual colonoscopies are often not able to detect polyps smaller than 10 mm, although regular colonoscopies can detect polyps of all sizes. And virtual colonoscopies do not allow doctors to remove tissue samples or polyps from the colon, whereas traditional colonoscopies can.
Since the benefits of the procedure aren’t made clear, we give the story a Not Satisfactory rating here.
The story briefly mentions radiation exposure and the potential for the need for a follow up colonoscopy if a suspicious lesion is found. In reality almost one third of routine colonoscopies identify a suspicious lesion that is either removed or is biopsied. That means that roughly one in three people undergoing a bowel preparation for a CT colonoscopy will need to undergo a second round for removal or biopsy of a suspicious lesion. That is a significant downside that should have been emphasized in the story.
The story does not cite any studies or research highlighting the merits of virtual colonoscopies. It includes enthusiastic statements about the detail being “remarkable” and that doctors can “walk through” the colon, with a supporting quote from one doctor. But where is the evidence? Research suggests that virtual colonoscopies have limits when detecting abnormal growths. The story claims, “such highly specific screening may allow doctors to detect more abnormal growths,” but this has not been proven. Studies have shown that virtual colonoscopies failed to detect lesions measuring 10 mm or more in 10 percent of patients. CT colonography also missed 15 percent of advanced cancers measuring over 6 mm.
The story calls colorectal cancer “the second leading cause of death among the combined group of men and women who have cancer.” That’s accurate, but we wish the story had also provided a person’s lifetime risk of developing colon cancer, which at 5% is more reassuring.
The CBS story quotes only one source, Dr. Arie Kaufman, and does not disclose the fact that he also happens to have invented the technology. An independent expert, who could have talked about the limitations of virtual colonoscopy and the benefits of traditional colonoscopy, would have been helpful.
The American Cancer Society provides a comprehensive listing of screening methods for colon cancer based on the level of risk of an individual. The story mentions a standard colonoscopy as an alternative as well as DNA tests and stool sampling.
The ability of a radiologist to take a virtual stroll through a patient’s bowel — i.e. the “walk-through colonoscopy” touted in the article — is perhaps unique to a single site. The story doesn’t establish whether or where such technology might be available outside of SUNY Stony Brook. But regardless of whether they provide the “walk-through” capability described here, most academic medical centers have the capability of performing a CT colonoscopy that’s the basis of this approach. Insurance coverage is a major consideration limiting its availability to the average patient
Virtual colonoscopies are not exactly new, since the technology was first patented in 1996. In 2004, 3-D virtual colonoscopy was approved for colon cancer screening in the US by the Food and Drug Administration. It seems that what may be new here is the projection of 3-D images on the wall, providing an “immersive” experience for the physician performing the procedure. But the story doesn’t establish that fact or specify what exactly the news is here.
The story includes an interview with Dr. Arie Kaufman, so it’s safe to say that it went beyond any news release.
Systematic, Criteria-Driven
Monday at #ADA2021, an infectious disease epidemiologist, a journalist, and a researcher shared perspectives on communication of risk in the era of COVID-19: http://ow.ly/ROfR30rMeE7 @AstleyCM @garyschwitzer @berthahidalgo @ADA_DiabetesPro
Shoutouts to @susan_bewley @drkevinknopf @MichaelBaum11 in this call for more than fawning coverage from press releases for these kinds of stories.
Also, linked history inside goes back 5 years just on Grail apparently trying to become Holy Grail. https://twitter.com/garyschwitzer/status/1408849696416841731
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