This story about a new way of performing a virtual colonoscopy explains what it does, what it does not do and why it probably won’t become a replacement for old-fashioned “scope procedures.” The story could have taken some cues, though, from a competing story in the Boston Globe that talked about costs and offered an exploration of alternatives that was missing here.
As the story notes, if people 50 or older were screened for colon cancer, more deaths would be averted, but the story is framed as if colonoscopy is the only screening option. It is not the only option. The American Cancer Society’s Dr. Len Lichtenfeld wrote HealthNewsReview.org recently to say, “As we clearly explain in the guidelines, there are several tests that can detect polyps before they become malignant, and those tests were listed as ‘preferred.’ Those tests do include colonoscopy, but they also include sigmoidoscopy, CT colonography, and even barium enema. The fecal occult blood tests (FOBT) and fecal immunochemical tests (FIT) primarily are used to detect cancer, although the guidelines clearly note they can also occasionally detect polyps if there is sufficient bleeding. Our expert panel was of the opinion that preventing cancer was a preferred strategy over detecting cancer, thus the differentiation.” The Boston Globe contacted the American Cancer Society about this research and did a nice job summing up the risks and benefits of different screening approaches.
The Journal skipped the cost question, which was unfortunate. The Boston Globe said, “Medicare doesn’t provide coverage for the imaging test, which Zalis said costs about one-third as much as the traditional scope screening.” Both of the outlets could have mentioned the range of possible costs for a traditional and virtual screening.
The story starts by making two claims. It says that the new technique “was shown in a new study to accurately detect larger precancerous polyps” and it also says that the procedure “was a better experience for patients. It backs the first claim up by saying that “The laxative-free scan accurately identified 91% of patients with polyps of 10 mm or larger — those at highest risk of becoming cancerous,” but it didn’t make clear – as MedPage Today did in its story – that “wasn’t significantly different than the rate of 95% with standard optical colonoscopy.”
There were no data presented to back up the second claim about patient experience. This may be a quibble given that avoiding the discomfort that comes with a colonscopy has to be a better experience, but we would have liked to have seen some attempt to quantify patient satisfaction. The promoters of virtual colonscopy make the claim, after all, that the main barrier to people being screened is a fear of discomfort.
With any claim about any new test, we expect to see both sensitivity and specificity details. MedPage Today reported: “For a diagnostic threshold of 8 or 6 mm, sensitivity was clinically significantly lower and specificity statistically significantly lower than with the conventional colon screen.” And they gave specific numbers. This story didn’t.
We preferred the way the Boston Globe handled this question. It said:
“Virtual colonoscopy, with or without prep, has some limitations. About one in five patients must undergo a standard colonoscopy after the imaging procedure to have suspicious looking polyps snipped off and biopsied. The CT scan also 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.”
In addition, MedPage Today reported:
CT imaging picked up indeterminate or potentially clinically important findings outside the colon in 16% and 3% of patients, respectively. Medical record review showed that 5.5% of the cohort ended up getting additional diagnostic work-up due to such incidental findings.
That could be a good thing – but it could bring potential harm in additional workups for some incidentalomas – things you caught that you really didn’t need to know about.
Again, we point to what MedPage Today reported for a more complete look at the limitations of the research:
The researchers cautioned that they had only three people reading all the images in the study and there were variations in their performance.
Other limitations were the size of the study and the quality of the survey data.
“Restricting study to a low-risk cohort limited the prevalence of lesions and the study’s statistical power, especially for polyps 10 mm or larger,” they added.
There was no disease mongering in the story.
The story includes some good contextual comments from Dr. James Aisenberg, a gastroenterologist and clinical professor of medicine at Mount Sinai Medical Center in New York. It also points out that there is a financial upside for the lead researcher in the study and the company that helped fund it: “Dr. Zalis and some of his co-investigators developed the software. The American Cancer Society, the National Institutes of Health and General Electric Co.’s health-care unit—which markets scanning devices and accessories—supported the researchers. Dr. Zalis says the company had no influence on the study.”
The story says that “In recent years, the use of computed tomographic colonography—known as CT or “virtual” colonoscopy—has eliminated the need for the most invasive part of the procedure.” That’s not entirely true. As the Boston Globe points out, 1 in 5 patients who have a virtual colonscopy still have to undergo a traditional scope procedure. Also, the story makes no mention of the other alternatives to colonscopy, most of which are discussed in the Boston Globe piece.
It is relatively clear from the story that while virtual colonoscopy is available as a treatment option, this method of preparing for a scan is not (“may become a useful alternative”).
The relative novelty of the “new method” using a software program to electronically “cleanse” the bowel was clear in the story.
The story does not rely on a press release.