The long-planned meeting between the CMS panel and representatives of the American College of Radiology's (ACR) Colon Cancer Committee is part of the ACR's ongoing effort to incorporate virtual colonoscopy (also known as CT colonography or CTC) as a colon cancer screening option to accompany conventional optical colonoscopy, flexible sigmoidoscopy, and stool testing. Citing the need for more research, the agency denied VC as a covered service in May 2009 after a campaign by ACR and other CTC advocates.
"We went through new evidence and talked about the specific areas that they had concerns about last time," said Dr. Judy Yee, who spoke by telephone with AuntMinnie.com shortly after the meeting ended on Tuesday. Yee chairs the ACR's Colon Cancer Committee and serves as professor and vice chair of radiology at the University of California, San Francisco.
ACR committee members Dr. Perry Pickhardt, professor of radiology at the University of Wisconsin, and Dr. Brooks Cash, chief of gastroenterology at the National Naval Medical Center, also attended Tuesday's meeting.
"Specifically, we talked about radiation dose, performance in a Medicare patient population -- we presented four new studies -- and extracolonic findings," Yee said.
Much research has been completed since May 2009, when CMS denied reimbursement for CTC screening, citing a need for more evidence in those three areas of research.
Yee noted the just-published study by Dr. C. Daniel Johnson and colleagues, zeroing in on CTC's sensitivity in the Medicare population that participated in the National CT Colonography Trial (ACRIN 6664). Other research examining CTC in older individuals includes a study by Dr. David Kim, Pickhardt, and colleagues that examined 577 individuals ages 65 to 79 from a cohort of nearly 6,000 patients undergoing CTC in Wisconsin (American Journal of Roentgenology, May 2009, Vol. 192:5, pp. 1332-1340). Cash and Dr. Michael Macari have also reported on the use of CTC for screening in older individuals, Yee said.
All of the studies examining the use of CTC in the Medicare population have been positive, concluding that "there's equivalent sensitivity and specificity comparing the younger and the older age cohort," Yee told AuntMinnie.com. Referrals for optical colonoscopy in older individuals range from about 12% to 14%, she said, a few percentage points higher than the referral rate for younger individuals, but a rate low enough to allow the vast majority of older screening patients to forego optical colonoscopy.
As for radiation dose, "we also talked about controversies regarding the linear no-threshold model," including two papers by David Brenner, PhD, and colleagues and one by Amy Berrington de González, PhD, et al, Yee said. In their 2011 AJR paper, for example, de González and her team examined the risk-benefit ratio of cancers prevented or induced by CTC, Yee said. Applying the ACRIN CTC protocol to the 2006 Biological Effects of Ionizing Radiation (BEIR) VII report and three independent microsimulation models, the authors estimated that the number of radiation-induced cancers from CTC screening every five years would be 150 per 100,000 -- far fewer than the 5,190 colon cancers prevented by screening every 100,000 patients.
In another AJR study, Macari et al looked at the prevalence of extracolonic findings in Medicare patients and found them to be infrequent and not requiring invasive follow-up.
Overall, the tone of the Tuesday meeting was quite positive, and the panel was cooperative, Yee said.
"I think they were actually very helpful in providing guidance as to next steps," she said. And by addressing the "parallel efforts" undertaken by CMS and the U.S. Preventive Services Task Force (USPSTF), the process will likely be more streamlined going forward, Yee said.
But there's work left to do. "We're not done yet," she said.