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Earlier this week, a news article in the New York Times regarding a recent retrospective study published in the Annals of Internal Medicine states that the Gold standard for colon cancer screening, the colonoscopy test, may be less accurate than previously reported.

In summary, the study concludes that instead of preventing 90% of cancers, as commonly believed, colonoscopies may prevent only 60% to 70% of colon cancer. The American Cancer Society (ACR) responded conservatively, given the evidence to date, that the ACR currently will not change its recommended intervals between screenings. As mentioned in an editorial in the Annals of Internal Medicine, perhaps one reason the ACR is not jumping into action at this point is that the Canadian study was retrospective, not prospectively designed. Next steps might include future prospectively designed randomized studies.

There are several theories on the potential sources for the increase reported in missed cancers in colonoscopy, including the skill of the colonoscopists, the cleanliness of the colon and the natural differences between the right and left sides of the colon. Regarding the skill level of the doctor, if those in the study were insufficiently trained, it may be that seeking out the most experienced endoscopists may help, but this can not be the only problem given another unpublished study purports similar findings. Regarding cleanliness of the bowel, it was raised that perhaps the bowel was not clean enough, especially on the right side, and while nearer term laxative is supported in the literature (see also a recent RSNA abstract SST07-06 that showed that superior patient experience related to reduced laxative regimens is frequently cited as a major benefit of virtual colonoscopy), the problems of the right side appear to be natural biology. In this regard, clusters of flat and indented polyps may progress to cancer rapidly are more common in the right colon.

Perhaps one method of improving cancer detection might be increased use of virtual CT colonoscopy, while not a solution yet, virtual colonoscopy may help in the future with the inspection the colon. Reflecting on presentations at the recently held 2008 meeting of the Radiological Society of North America (RSNA), one abstract (LL-GI3193) presented the current understanding of the utility, acquisition, and analysis along with advantages and limitations of CT colonography in patients who have undergone incomplete colonoscopy. Another abstract (SSA06-09) might support that CT colonography measurements have a higher accuracy than colonoscopy measurements. Certainly though, significant challenges remain for the use of virtual CT colonoscopy (as discussed in a RSNA plenary session PS60) since although CT colonography can provide a time-efficient, noninvasive structural examination of the whole colon, the many achievements gained are countered by significant challenges to overcome.

Audio Interviews

Dr. Michael Macari, NYU Medical School, provided an academic perspective on the use of colonoscopy and virtual colonoscopy ...

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Dr. Ayso de Vries, Academic Medical Center in Amsterdam, Netherlands, explained the importance of reducing the burden of bowel prep...

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Dr. Mark Klein, Washington Radiology Associates, P.C., gave his thoughts on current and future use of virtual colonoscopy ...

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