Like a long-frozen glacier slipping off an ice shelf, organized gastroenterology is warming to the idea of virtual colonoscopy as a component of colon cancer screening. Whether the floe will eventually collide with radiology is an open question.
Evidence of the thaw comes from a recent report by the American Gastroenterological Association (AGA), whose conclusions represent a sea change for gastroenterology. Gastroenterologists would not only accept virtual colonoscopy -- a technology some have characterized as inadequate, uneven, and unproven -- but according to the report, they would bypass radiology entirely and perform it on their own.
"It is the position of the American Gastroenterological Association Institute that gastroenterologists should be able to use and manage any technology that will enable them to deliver better patient care, even if that technology is computed tomographic colonography (CTC or virtual colonoscopy [VC]), a controversial imaging test that has divided some in the gastroenterological community," begins the November report from the AGA's Future Trends Committee (Gastroenterology, November 2006, Vol. 131:5, pp. 1627-1628).
Praise for scanning
To be sure, many prominent gastroenterologists have supported the idea of VC screening all along, reserving their final approval (along with many radiologists) only for the day when a second large multicenter trial demonstrates consistently high accuracy.
"Virtual colonoscopy ... seems to hold great promise for the detection of significant lesions within the colon, and provides an excellent opportunity for collaborations with abdominal radiologists," wrote gastroenterologist Dr. Bernard Levin in an e-mail to AuntMinnie.com. Levin, who is not associated with the AGA report or its authors, is vice president for cancer prevention and population sciences at the University of Texas M. D. Anderson Cancer Center in Houston.
"I believe that gastroenterologists should become familiar with all new technologies including virtual colonoscopy that enhance the care of their patients," Levin wrote.
Virtual colonoscopy is an exciting technology that has evolved rapidly, said Dr. David Lieberman, a professor of medicine and chief of gastroenterology at Oregon Health and Science University in Portland, in an interview with AuntMinnie.com. "It doesn't surprise me that members of the GI community might want to embrace it if it's useful in terms of providing GI care for people." Close coordination with radiologists will probably be an important element of any practice model, he said.
According to Dr. Robert Sandler, vice president of the AGA Institute and Future Trends Committee member, the report is entirely consistent with the organization's longstanding favorable view of VC as a potentially important technology.
"The AGA has had an open mind about CT colonography, and in fact has advocated for a category I CPT code so that physicians could get paid for CTC," Sandler told AuntMinnie.com in an interview, noting that other organizations, such as the American College of Gastroenterology (ACG), have been more critical.
The leader of the Future Trends Committee, Dr. Timothy Cragin Wang, also spoke to AuntMinnie.com. Wang is a professor of medicine and chief of gastroenterology at Columbia University Medical Center in New York City.
Wang acknowledged an economic inducement to perform VC in gastroenterology practices, but said the committee's real task was to make the AGA Institute "more nimble as an organization and more forward-thinking" by first imagining the gastroenterology practice of the future, evaluating all of the emerging technologies that might play a role in it, then planning for their incorporation.
"I think the general consensus was that there would probably be a little less screening colonoscopy, and probably more colonoscopy with the point of view of taking out the polyps rather than initially detecting them," Wang said.
Thus, "in the not-too-distant future," virtual colonoscopy "may exert significant influence on how the field is defined," the report authors stated.
VC was "one of the issues that caught the attention of the Futures Committee because it could be a revolutionary technology if proven, and could be a primary way to screen for colorectal cancer in the future," Sandler said.
Learning to read
The report cautions that despite VC's "many theoretical advantages ... a number of issues, including relative sensitivity, technological challenges, standardization of test performance, and cost and reimbursement issues, need to be addressed before (VC) is broadly accepted as a viable alternative to conventional colonoscopy for colorectal cancer screening."
Gastroenterologists are of many opinions on virtual colonoscopy, Sandler said. "There are those who think CTC technology is viable; there are early adopters that would like a chance to participate. There's a group of people who think that the advantages of optical colonoscopy make it a better screening test for colon cancer in that if any lesions are found they can be removed. Then there are people who say wait and see."
Economic issues aside, why would a gastroenterologist want to perform the exam?
"I think that the position of the AGA is that gastroenterologists have devoted a lot of their career to examining the colon, and therefore it would not be inappropriate for gastroenterologists to examine the colon with CT scans with appropriate training and credentialing," Sandler said. "It's not awfully different from cardiologists doing nuclear angiography or gynecologists doing ultrasound of the pelvis. Physicians other than radiologists have done imaging studies in lots of different areas."
The report outlines the AGA Institute's plans, in cooperation with three other gastroenterology societies, to implement VC in gastroenterology practices. Gastroenterology will develop its own training standards for performing VC, and a business model that gastroenterologists can use to incorporate the exam into their practices. The first training session for gastroenterologists will take place sometime this year, though details have not been finalized.
Lieberman said it may be premature for gastroenterology to embrace VC before the technology has shown proven results -- for example, in multicenter trials such as the National CT Colonography Trial (ACRIN 6664), for which results are expected later this year. "To me, it's putting the cart before the horse," he said. And despite some success with the virtual exam in academic and elite centers, "we don't know how VC performs in the ... community setting."
"The initiative that gastroenterology wants to be more involved with CT colonography is good news," wrote Dr. Elizabeth McFarland, an adjunct professor at the Mallinckrodt Institute of Radiology in St. Louis and leader of the Reston, VA-based American College of Radiology's VC task force, in an e-mail to AuntMinnie.com. "Other disciplines, including gastroenterology, will be essential to shape its further development. In today's pay-for-performance environment, whoever performs and reads it will have to meet defined quality standards. The potential of CTC to increase colorectal screening and/or surveillance of specific patient cohorts will only be realized with effective collaborations and efforts."
Polyp pitfalls
Other radiologists contacted for this story took a dim view of the gastroenterology initiative.
Dr. Abraham Dachman, a professor of radiology at the University of Chicago, said VC is more complex than the casual observer might realize, and is probably not time-efficient for the nonradiologist to learn.
"High-quality screening and diagnostic CT colonography requires quality assurance by the CT technologist while the patient is in the CT suite, and sometimes additional scanning in different positions or with intravenous contrast is helpful," he wrote in an e-mail to AuntMinnie.com. "The reader must be able to respond to these technical questions."
Analogous to the American College of Cardiology Foundation (ACCF) and American Heart Association (AHA) consensus statement on clinical competence for cardiac imaging (Journal of the American College of Cardiology, July 19, 2005, Vol. 486:2, pp. 383-402), Dachman said the reader must be knowledgeable and certified in the use of radiation and intravenous contrast agents.
"This is not intrinsic to the skills of a nonradiologist," he wrote. "If a nonradiologist cannot supervise a CT technologist doing a difficult scan, then they had best not get involved in interpreting the exam."
Dachman also stressed the importance of extracolonic findings, an area in which gastroenterologists cannot be expected to have the training to read adequately.
"Clinically important extracolonic findings are more common in nonscreening cohorts, but even in screening cohorts, represent a low-cost patient benefit," he wrote. Even at low radiation doses, findings can be conspicuous and pose a medicolegal risk to any nonradiologist venturing to interpret CTC."
Sandler responded that following up on extracolonic findings creates risks of its own, and said that in any case radiologists could be hired to look for them, even based outside the U.S. if necessary.
"Extracolonic findings will be a big problem for the erstwhile gastroenterologist CTC reader," according to Dr. Joseph Ferrucci, a professor of radiology at Boston Medical Center in Massachusetts. "Reputable radiologists won't touch the inevitable murky offer for a split-read contract. Malpractice liability for reading errors will be a threat," he wrote in an e-mail to AuntMinnie.com.
Dr. Judy Yee, a professor of medicine and chief of radiology at San Francisco VA Medical Center, said the learning curve for nonradiologists would be very steep.
"The interpretation of CTC includes expert training in not only the 3D endoluminal fly-through, but how to use 2D axial and multiplanar reformat views interactively with the 3D views," Yee wrote in an e-mail to AuntMinnie.com. "Gastroenterologists typically have no training in CT technology or interpretation. Radiologists have realized that there is a steep learning curve for CTC, and this is true even for readers who have prior CT experience. Unless the gastroenterologists are willing to devote significant time for training in this technique ... then it is better in the hands of radiologists."
Pitfalls relating to reading proficiency and extracolonic abnormalities among nonradiologists will certainly need to be addressed, Levin wrote. "In the best situations, the collaborations between radiologists and gastroenterologist will ensure quality," he stated.
Wang declined to discuss questions about reading proficiency or liability, saying his job as the Future Trends Committee leader was to describe in broad strokes the potential technologies gastroenterologists should evaluate -- not the details of how a gastroenterology-led VC practice might unfold in the clinical setting. As for extracolonic findings, he said they "should probably be read -- and probably by a radiologist."
"Except for the obvious financial incentives, it is not clear why gastroenterologists, who claim that there are not enough of them to perform all the required screening colonoscopies in this country, would want to take on a new technique that would be time-consuming for them and take them away from what they do best," Yee wrote. The resulting strain on manpower "could also have negative consequences for patients," she stated.
The idea, Sandler responded, is that by incorporating virtual colonoscopy into the screening mix, gastroenterologists would free up some of the time they previously spent performing optical colonoscopy, easing at least to some extent the capacity shortage for optical colonoscopy that is expected to worsen as the U.S. population continues to age.
Citing time constraints, Dr. Douglas Rex, a gastroenterologist and professor of medicine at the Indiana University School of Medicine in Indianapolis, declined to comment for this article. But in a November 14, 2006, New York Times article he suggested that gastroenterologists are busy enough already.
"We have a lot of organs," Rex told the newspaper. "The esophagus, the stomach, the small bowel, the liver, the pancreas -- I think we've got a lot to do."
Wang told AuntMinnie.com that he agreed with Rex, adding, "in general, the way gastroenterologists do our specialty is that we should be the primary physicians for all digestive diseases, all digestive organs. So whatever screening test is decided, we probably will need to play a major role, at least in evaluating the technology, deciding what's best for the patients, both diagnosing the diseases and following up on the diseases. So whether or not it makes sense for gastroenterologists to do VC, I don't know the answer to that. But we probably need to play a major role."
One reason: Gastroenterologists tend to be better at patient care, according to Sandler.
"The difference between gastroenterologists and the radiologists is that we sit down with the patients and sort of discuss options," Sandler said. "The radiologists are often on the receiving end for patients who are referred from other physicians. We might explain to someone over 50 that there's about a 30% chance they'll have a polyp.... There are two technologies: there's one (colonoscopy) where we remove what we see, and there's the other (CTC) where we refer what we see and we ignore what we don't see."
"Smart radiologists will bypass gastroenterologists entirely and market CTC directly to primary care providers," Ferrucci wrote. "The paradigm is mammography, which has largely displaced breast surgeons out of the business of breast cancer screening."
Gastroenterologists "can't do everything," Wang said. "But the radiologists couldn't probably currently do it either. And I don't know how it's all going to work out, but I think everyone agrees that we need more colorectal cancer screening."
Dr. Perry Pickhardt, a radiologist and associate professor of radiology at the University of Wisconsin in Madison, had no qualms about gastroenterologists performing VC.
"I welcome the few gastroenterologists who might actually do it well," Pickhardt wrote in an e-mail to AuntMinnie.com. "But most will struggle mightily."
By Eric Barnes
AuntMinnie.com staff writer
January 25, 2006
Related Reading
Slow colonoscope removal increases odds of spotting lesions, December 14, 2006
Colonoscopy declines at VA: Is limited capacity to blame? November 13, 2006
New data reveal higher efficacy for primary VC screening, October 18, 2006
VC finds risky polyps, might reduce polypectomies, June 8, 2006
Gastroenterologist surveys target lesions, VC practice, March 20, 2006
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