3D CTC image and corresponding endoscopic image of 25 mm pedunculated polyp in 71-year-old man. Source: Am Jour Roent 2012;199:W27-W34

CT colonography (CTC) has received another boost from researchers, as a new study of Medicare-aged patients reinforced CTC as a screening tool for colorectal cancer (CRC), according to results published in the July issue of the American Journal of Roentgenology.

The authors indicated the findings should further fuel the debate over coverage for the procedure. In 2009, the Centers for Medicare and Medicaid Services (CMS) said CTC would not be covered due to a lack of outcomes data specific to the Medicare population.

“These results provide previously unavailable information regarding outcomes associated with CTC in older patients and should be considered carefully by policy makers when making coverage and public health implementation decisions regarding CTC screening for the Medicare-eligible population,” wrote Brooks Cash, MD, of the National Naval Medical Center in Bethesda, Md., and colleagues.

“Given the wide acceptance of the value of CTC as a CRC screening test and the increasing amount of data supporting the practice in older patients, we believe that CTC screening and surveillance for CRC in Medicare-aged patients is a viable alternative to other tests and should be reconsidered for endorsement by both the [U.S. Preventive Services Task Force] and CMS.”

The study evaluated outcomes in 1,410 consecutive Medicare-aged patients who underwent screening or surveillance CTC as part of the Colon Health Initiative at the authors’ institution. The patients were screened between 2004 and 2009.

Results showed that, based on a polyp size threshold of 6 mm, the percentage of patients who would have been referred to colonoscopy as a result of CTC was 14.5 percent. This rate is similar to the rate found by other studies of younger populations, according to the authors.

Colorectal neoplasia and advanced neoplasia were found in 9.3 percent and 3.3 percent of patients, respectively. Potentially important extracolonic findings were observed in 2.9 percent.

“The low rates of referral to colonoscopy, prevalence of advanced neoplasia, and prevalence of extracolonic findings make CTC a viable option for Medicare-aged patients,” summed Cash and colleagues.

Addressing concerns about the radiation dose of CTC, Cash explained the average dose with CTC in the current study was calculated to be 4.24 mSv per exam. “To put that in perspective, the average yearly radiation exposure of American adults is about 6.2 mSv,” Cash said in a release.

Only about half of patients eligible for colon cancer screening undergo any type of screening exam, and previous studies have shown that up to 40 percent of those undergoing CTC said they would not have been screened had CTC not been an option.

“This is the real value of CT colonography–offering an alternative, high quality, total colonic preventative screening to a large percentage of the population that either refuses or is unable to undergo colonoscopy,” said Cash.