July 30, 2012

Virtual Colonoscopy — Turf War and Peace
By Beth W. Orenstein
For The Record
Vol. 24 No. 14 P. 22

While some radiologists and gastroenterologists clash over colon cancer screening techniques, a Wisconsin healthcare system found a way for the specialties to work together in the hopes of increasing the number of people screened.

When virtual colonoscopy (VC)—also called CT colonography (CTC)—was introduced in the early 1990s, the hope was that because it was less invasive, didn’t require sedation, and would be more comfortable than traditional colonoscopies, more people would comply with the American Cancer Society’s screening recommendations for colorectal cancer.

But that never happened. Colorectal cancer is the second leading cause of cancer deaths in the United States behind lung cancer. Even though most patients know that the early diagnosis and treatment of colorectal cancer could save their life, less than one-half of those over the age of 50 who should have routine screening colonoscopies every five to 10 years do so.

One key issue that has kept VCs from becoming popular is reimbursement, says Abraham Dachman, MD, of the University of Chicago Medical Center, a nationally known specialist in abdominal imaging. In May 2009, the Centers for Medicare & Medicaid Services (CMS) denied a request for Medicare reimbursement for VC. The CMS cited three principal areas that needed more research: the radiation dose associated with the procedure, VC results in Medicare-aged populations, and extracolonic findings.

In announcing its decision, the CMS also noted that the year before, the US Preventive Services Task Force had refused to give its stamp of approval to VCs. (In 2008, in a joint guideline, the Multi-Society Task Force, the American Cancer Society, and the American College of Radiology added CTC to its list of recommended colorectal cancer screening tests.)

Even though today many third-party payers reimburse for VCs and more than 25 states mandate VC coverage, the procedure is not gaining popularity. “I think it’s not growing very much because people are waiting for Medicare,” Dachman says.

Mark Baumel, MD, MS, president and CEO of Colon Health Centers of America, based in Mendenhall, Pennsylvania, agrees: “Virtual colonoscopy hasn’t been gaining acceptance with any kind of wild velocity because of that issue. If Medicare says it’s not a good test, you have to overcome that to convince people that it is. It has largely been in standstill mode since the Medicare decision.”

The CMS indicated it would revisit the issue when its areas of concern were addressed and more favorable evidence came to light, but it has not reconsidered its decision at this point, Baumel says.

Turf and Teamwork
Turf wars also have prevented CTC from catching on. Radiologists who perform VCs are sometimes seen as treading on gastroenterologists’ territory, which has led each specialty to promote the advantages of its method and the disadvantages of the other’s.

Radiologists tout the comfort and convenience of CTC. While patients must prepare for CTC the same way they do for an optical colonoscopy, CTC is a shorter exam (about 15 minutes) and patients don’t require sedation. Radiologists also argue that CTC is safer even with the radiation and that the risk of perforating the colon is negligible and much lower than with optical colonoscopies.

Gastroenterologists counter that the biggest advantage to an optical colonoscopy is that potentially precancerous polyps can be removed immediately if found, whereas radiologists who find questionable polyps must send the patient for an optical colonoscopy, requiring a second round of cleansing prep.

Baumel believes radiologists aren’t pushing VCs as much as gastroenterologists are pulling them. “Radiologists have not been promoting it nearly as strongly as [gastroenterologists] have been criticizing it,” he says.

Baumel believes it’s a scope-of-practice issue. CTC is just one of dozens of tests that radiologists perform. “Virtual colonoscopies are not going to revolutionize radiologists’ professional work lives,” he says. But if VCs were to take hold, it could revolutionize gastroenterologists’ professional lives. “Gastroenterologists have a lot more to lose than radiologists have to gain if more people undergo CTC,” Baumel says.

In the interest of increasing colorectal cancer screenings, some radiologists and gastroenterologists have begun working together and, while integrated programs are small in number, they seem to be working well.

Radiologists at the University of Wisconsin Hospitals and Clinics in Madison work with gastroenterologists so that if, when doing a VC, a radiologist finds a potentially precancerous polyp that needs to be biopsied or removed, it can be done the same day with the same prep.

Many are skeptical that such an arrangement can work, says David Kim, MD, a radiologist and researcher who performs the VCs at Wisconsin. “People say there’s no way you can do that. It’s hard to get an add-on because the gastroenterologists are so busy,” he says. “But we have a good relationship with the gastroenterologists, and they’re happy to add on a case for the patients, if necessary.”

Besides, Kim says few patients need to be seen by the gastroenterologists. “If you’re screening 10 patients in the morning, one, maybe two, needs to go on to optical colonoscopy, and many days there are none,” he says.

At the 2011 Radiological Society of North America annual conference, Kim presented research, later published in Radiology, that found of 577 patients aged 65 to 79 who were screened with CTC, 88 (15.3%) were referred for optical colonoscopy because polyps were larger than 6 mm. “The referral rate drops below 10% for our younger screen-eligible population,” Kim notes.

Kim says several researchers have looked at patient preferences and at least one study found about one-third of patients said they would not have undergone screening for colorectal cancer if not for the virtual option. “It appeals to people because with CTC you don’t need sedation and you’re always in control,” he says. (When President Obama had his physical in 2010, he underwent a VC so he could remain conscious and not have to temporarily transfer authority to the vice president.)

Increasing Screening
Kim’s colleague, Jennifer Weiss, MD, MS, says the reason she and her fellow gastroenterologists are eager to work with the radiologists at Wisconsin is to increase colon cancer screenings performed by the healthcare system. “Whether it’s by CTC, optical colonoscopy, or stool tests, we just want to increase our screening rates overall,” she says.

That’s why she’s happy to make the screening process as seamless as possible for patients who choose VCs and find they also need an optical colonoscopy. “If they have a polyp on CTC and want to have an optical the same day, we try and fit them in, although sometimes they didn’t make arrangements to have a ride or be off from work for the rest of the day,” she says.

There is some controversy over whether small polyps (those measuring less than 5 mm) even need to be removed or biopsied. “As gastroenterologists, we remove small polyps,” Weiss says, but they may not even show up on VCs.

Flat polyps also are a subject of debate. “We are recognizing them more frequently on the right side of the colon and, with our improved optics, we can detect them better than with virtual colonoscopies,” Weiss says. “We have different filters that change the wavelength of light and enhance the vascular pattern on the surface of the polyps to make them stand out more. There is a concern that these are polyps virtual colonoscopy can miss. However, in our system, we are seeing a lot of flat polyps caught on CTC that are referred to us for optical colonoscopy.”

At the same time, some polyps are more easily identified on CTC. For example, “Virtual colonoscopy is better at seeing things behind folds,” Weiss says. “Of course, a good endoscopist should look behind all the folds, too.”

In addition, in some cases, optical colonoscopies cannot examine the entire colon. In those cases, “The gastroenterologists will refer these optical colonoscopy patients to us,” Kim says. Patients may have undergone previous abdominal surgeries or have body shapes that can make it difficult to get the colonoscope to the beginning of the colon. “They can send those patients for CTCs, and we’ll look at the parts where they can’t reach,” he says.

VCs also are ideal for patients with medical conditions for which sedation would be contraindicated (eg, severe chronic obstructive pulmonary disease, allergic reactions to sedative medications) and for patients taking blood thinners, Kim notes.

Colon Health Centers of America’s business model is to set up and operate integrated VC centers in partnership with community-based gastroenterology groups. At integrated centers, patients can undergo a VC and, if polyp removal is needed, can have an optical colonoscopy the same day.

“We never offered stand-alone virtual colonoscopy because we don’t think it’s the right thing to do for patients,” Baumel says. “With integrated VC, the study is read immediately, and the patients know whether they can go home or to work because their colon is ‘clean’ or whether they have a polyp that needs to be removed. Those patients with found polyps can have them removed immediately without the need for a second prep. The preparations for virtual and optical colonoscopy are slightly different but can work for both tests.”

Baumel says his colon health centers had hoped to set up dozens of its proprietary integrated VC centers across the country by now. It had five or six sites in the design stage in 2009 when Medicare decided not to cover VCs as a screening procedure for colon cancer. He’s confident that the model would have taken off had the decision been different, and he’s hoping that interest will grow as patients have slowly increased their demand for VCs.

Cost and Decision Making
Dachman says VCs cost less than one-third of traditional optical colonoscopies depending on where they’re performed. Academic centers charge between $900 and $1,200 for VCs, whereas an optical colonoscopy can be $3,000 to $4,000. The pathology on any polyps is separate.

“The logic of virtual colonoscopy is it is cost-effective at screening patients,” Dachman says. “If someone has a high risk of having lesions and a strong family history, they should go straight to optical colonoscopies. But for most of the population who doesn’t have that increased risk, it makes much more sense to have a virtual colonoscopy where you’re likely to have a normal exam,” he says. Gastroenterologists can fill their schedules with people who are more likely to have abnormal exams. “That’s the logic I buy into,” Dachman says.

Radiologists don’t believe the radiation from VCs should be part of the debate; they say it’s a nonissue. Baumel believes that much of the concern about radiation exposure from CTC comes from those who are against its implementation, not from scientific data.

Baumel and his colleagues also point out that the exam’s radiation dose is extremely low. “It’s about one-third the dose of regular abdominal pelvic CT scan,” Baumel says, noting it really shouldn’t be a concern.

Kim says the number of colon cancers that would be detected if more people were screened would be far greater and therefore outweigh the theoretic possibility of a patient developing a future cancer from the screening radiation. “People are still bringing up the radiation objection,” Dachman adds, “but it’s an extremely weak argument. There’s no evidence of increased cancer at the kind of low doses we’re using for VCs, and there never will be based on our current knowledge.”

Using CAD
Computer-aided detection (CAD) for reading virtual exams has been improving, Kim says. The improvements have convinced him that it’s worth using in many cases. “My views have evolved,” he explains. “Originally, I thought it would have very little utility. Now I find it’s almost like a spell check. You finish reading the study and turn on CAD and make sure you didn’t miss something. It’s an added layer of redundancy to make sure you don’t miss a polyp.” Kim doesn’t use CAD on every exam he reads because it takes some time to process.

The radiologists interviewed for this article also believe the argument against CTC—that it could find more than colon cancers and result in unnecessary testing and biopsies—has little merit. In a 2010 paper for the Gastrointestinal Endoscopy Clinics of North America, Judy Yee, MD, of the University of California, San Francisco, pointed out that “most extracolonic findings are determined to be clinically inconsequential on CTC, and most patients are not recommended for further testing.” However, she said, some findings can lead to the earlier diagnosis of a clinically significant lesion, “which could result in decreased patient morbidity and mortality as well as overall savings in downstream healthcare costs.”

If patients could undergo VC without having to cleanse their bowels, would it become the modality of choice and encourage even more people to undergo screening? One possibility of improving the prep for VCs is to use fecal tagging. When the CT is performed, residual fecal material appears white. Could computer-generated fecal subtraction techniques be used to remove the high attenuation and leave only the mucous membrane of the colon and rectum and any colorectal cancers or polyps? Kim says the idea has great potential, but more research is needed.

Dachman says the arguments against CTC for colorectal cancer screening are out of date and wishes that the virtual procedure could become more available, especially if doing so were to increase colon cancer screening rates.

“Each test has its advantages and disadvantages,” he says. “I’m not telling anyone what to do, but I’m arguing for truthful disclosure.”

— Beth W. Orenstein is a freelance medical writer in Northampton, Pennsylvania.