CT Colonography: Ready for Prime Time

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On June 18, 2008, a letter was sent to the CMS Coverage and Analysis Group seeking approval of CT colonography (CTC) as a generalized screening tool for colorectal cancer among asymptomatic Medicare patients 50 years of age or older. The letter itself was a calm recitation of years of evidence collected through studies and trials of CTC in various patient groups, including the large, multicenter ACR Imaging Network (ACRIN) trial recently completed. The letter was sent in response to a call from CMS for comment on a national coverage analysis of CTC. The letter, sent under the sponsorship of the ACR, the Society of Gastrointestinal Radiologists, and the Society of Computed Body Tomography & Magnetic Resonance, hardly appeared, on its face, to mark a watershed event, but the response to CMS may have been one.
imageJudy Yee, MD
CTC, commonly called virtual colonoscopy (a name that the ACR is trying to discourage), has been on the horizon for years. Its practitioners have patiently developed it through several generations of CT scanners and have seen its utility and accuracy increase with the introduction of 2D and 3D postprocessing software and workstations. For all this, CTC has remained largely an out-of-pocket expense. At the same time, over 60% of those at risk for colon cancer are going unscreened.
imageBibb Allen, MD
Now, that could change. If CMS approves CTC as a generalized screening tool, the impact on patients, payors, radiology groups, and certain nonradiology physicians could be momentous, both clinically and financially. Events Prior to the Letter While she was not a signatory to the June 18 letter, Judy Yee, MD, was one of its authors. She and her colleagues worked quickly to prepare the letter once CMS called for comment on CTC. She says, “There was a short window. It was 30 days.” Yee is chief of radiology at the San Francisco VA Medical Center and is also professor and vice chair of the department of radiology and biomedical imaging at the University of California–San Francisco (UCSF). She has been a pioneer of CTC through studies at the VA and elsewhere. She has also developed national guidelines for performing CTC screening, and she teaches CTC at the UCSF medical school. Yee says that a rapid succession of events stimulated the CMS call for comment and the writing of the June 18 letter. First, in late 2007, the results of the ACRIN trial were released. They showed excellent performance for CTC as a screening tool, Yee says, with sensitivity rates of 90% and specificity rates of 86% for precancerous polyps of 10 mm or more. These rates were comparable to those for the gold standard in colorectal-cancer detection, the optical colonoscopy (OC), Yee adds. The second stimulus, Yee says, was the 2007 publication of a study1 directly comparing CTC with OC; it found similar detection rates for advanced adenomas. A significant factor in that study, Yee adds, was that the number of polypectomies was four times higher in the OC-only group than in the CTC group, meaning that polyp removal for the CTC patients who later underwent OC and surgery was more efficient. The third stimulus behind the CMS call for comment and the June 18 letter was perhaps the most critical, Yee says. That came in March 2008, when the American Cancer Society added CTC to its list of screening options for colorectal cancer. “For the first time, there was endorsement of CTC as a valid option for screening for colorectal cancer,” Yee says. The Clinical Impact While CMS won’t act on CTC approval for screening until all comments have been analyzed, Yee says that she’s optimistic. “My take on this is that CTC has really been proven,” she says. “I think the ACRIN trial showed this is an excellent test, with a less invasive option for getting the screening done.” If CTC is approved by CMS—and if other payors follow the CMS lead with their own approval—then the clinical picture of colorectal cancer in the United States could be hugely altered. For one thing, Yee says, many more patients will be screened for precursor polyps before their cancers can develop. Because OC requires an instrument to be inserted into the colon, most asymptomatic patients opt out of screening. “Currently, less than 40% of those who should be screened are actually getting screened,” Yee says. “This is with the options of colonoscopy, barium enema, or flexible sigmoidoscopy.” Most people continue to rely on a routine fecal occult-blood test (FOBT), but the FOBT will only detect bleeding cancers. It won’t detect the all-important precancerous polyps that CTC finds, Yee says, because they don’t usually bleed. In addition, she says, well-developed cancers often bleed only intermittently and are missed on FOBT. If CTC could become as common a screening tool for colon cancer as mammography is for breast cancer, it might alter the death rate of the disease radically. Colon cancer is now the third most commonly diagnosed cancer in the United States and the second leading cause of cancer deaths, according to the June 18 letter. “We are an aging population, with 75 million Americans at 50 plus, and we are adding four to five million additional subjects per year,” Yee says. This adds up to a potential for millions of CTC exams to be done, she adds. “It would change the algorithm of how we work up and treat colon cancer.” Indeed, one of the primary goals announced by the American Cancer Society in adding CTC as a screening option was a focus on colon cancer prevention, not just treatment. A clinical side benefit of CTC, and one not shared with the other colon-cancer–screening methods, is that radiologists interpreting CTC can also look for extracolonic findings like aortic aneurysms, kidney cancers, and lung cancers. This is not a small consideration. “There are clinically important extracolonic findings in 5% of asymptomatic patients who undergo CTC,” Yee says. Implementation CMS has indicated that it will make its CTC coverage decisions by February 2009. Between now and then, radiology groups and other practitioners have time to contemplate whether, and how, they will provide CTC, assuming that demand will increase if there is Medicare funding. Yee says that most radiology groups already have multislice CT scanners and would, at most, need to add CTC software and purchase a carbon-dioxide colon inflator. Neither is a heavy expense. From an equipment point of view, CTC would not be difficult for radiology groups to roll out, she notes. While some groups are waiting for CMS approval, many already have the equipment. Interpreting CTC is not for the untrained. The ACR recommends that radiologists interpret at least 50 cases under supervision before they do so alone. Yee says that training courses, including ACR courses and those offered through universities, are proliferating rapidly. “The educational opportunities are there,” Yee says. One of the big steps in providing CTC will be developing ways to streamline patient management and care so that there is rapid evaluation for treatment, whether it’s a follow-up colonoscopy or surgery in cases where colon polyps or cancers are found, Yee says. “I do think it’s really important, at this juncture, that the pertinent societies and physician groups invested in this work together collaboratively,” she adds. “The leadership has to set the tone and the model.” The ACR is working on metrics to be applied for accreditation standards for CTC and is developing reimbursement standards similar to those now used in mammography, Yee says. While the ACR is asking CMS to approve CTC screening for asymptomatic patients aged 50 or over, the screening intervals (and how CTC might be used in combination with OC and other procedures) are still under study. “The CTC screen currently is good for five years,” Yee says. “That may change. It may become 10 years. It also depends on comorbidities.” The guideline for OC screening is currently every 10 years, she notes. CTC Economics While radiologists may be optimistic about the rollout of CTC and the lives that it may save through colon-cancer prevention, nobody knows how many patients who are averse to OC or other procedures will actually show up for CTC screening. Nobody knows what the outcomes will be, economically, if CTC screening discovers more cancers that have to be treated at the same time that more precursor lesions are being removed to prevent cancer. Would routine CTC screening add to or subtract from overall national health care expenses? “That’s hard to answer,” Yee says. “I think the hope is that the bill will go down, but you’re talking about a lot of intangibles. It will cost more to do the screening, but we hope that it will catch or prevent colon cancer at an earlier stage, and that will be a cost savings—so that’s a balance.” Yee also notes the human factor in all those whose cancer may be curtailed or prevented by CTC, but what is the cost benefit of not undergoing surgery or chemotherapy? How to weigh the added cost of CTC screening against savings on surgery and treatment is a mystery, for now. “Nobody knows how that will balance out,” Yee says. Probably Not a Gold Mine Bibb Allen, Jr, MD, is a body-imaging subspecialist with the Birmingham Radiological Group, which covers that Alabama city’s Trinity Medical Center. Allen is also chair of the ACR’s commission on economics. The commission has been assessing the likely economic impact of wider CTC implementation. “The main economic issue is that it is a coverage issue,” Allen says. “We hope that CMS will decide that CT screening colonography should become a covered benefit.” Allen cautions that this may not happen, pointing out that there are many ways that CMS can go. He says, “They have any number of choices: coverage with evidence development (where patients have to be enrolled in a study), no additional approval pending study, or complete coverage. We don’t know exactly how they will respond. We are optimistic for a favorable decision.” Based on the Cancer Society’s listing of CTC, which he calls a key factor, Allen says that he thinks that CTC will be covered by CMS. Will it create additional income for radiology practices? Allen says, “Having increased volume and having another niche of patients could certainly add revenue to practices, but we’re focused on what is best for beneficiaries and on obtaining coverage now that we think the science is there. The economics are yet to be determined. A lot depends on the way the CPT® codes are developed and the way the new medical services are valued.” He continues, “We think radiology should be providing this service, and to the extent it increases volume, that’s good—but we won’t be getting paid more for doing less.” Allen says that the out-of-pocket cost of CTC screening now ranges from $700 to $1,500, depending on location, stool-tagging expenses, and postprocessing charges; but he says that isn’t indicative of what CMS may pay for CTC screening. The AMA must also assess RVUs for the procedure, he adds. “Until we know what all the recommendations are, it’s hard to predict.” Losers Like Yee, Allen thinks there will undoubtedly be some turf warfare between radiologists and nonradiologist physicians who gear up to offer CTC themselves. He says that this is just another reflection of technological change in medicine. “We believe this procedure is comfortable at home with radiology,” he says, “but that doesn’t mean nonradiologists won’t try to do it. The turf battles are bound to occur, but we hope, whatever CMS does with coverage, they will see the need for training and the demonstration of training.” While some procedures, such as the double-contrast barium enema, may be eclipsed by the greater accuracy of CTC (as referenced in the June 18 letter), Allen says that he doesn’t see a situation where the deployment of CTC will make economic losers out of some nonradiology practitioners. “Gastroenterologists are probably worried, but I assume there will be plenty of business to go around. If more polyps are found, then gastroenterologists will have more polyps to remove,” he says. Allen doesn’t think that CTC screening will increase radiologists’ malpractice costs. He says, “So far, we haven’t seen anything like that with coronary CT angiography, so I don’t foresee it. Mammography remains the biggest malpractice threat for radiologists.” Allen says that he anticipates the discussions that will take place from now until February, now that CMS has CTC approval squarely on its agenda. “It will be an interesting few months,” he says.