SUNDAY, July 1, 2012 (MedPage Today) — CT colonography screening in nearly 1,400 Medicare-aged patients had results similar to those seen in younger populations, researchers reported.

A little over 14 percent of patients 65 and older were referred for colonoscopy after the scanning found polyps of 6 mm or greater, according to Brooks Cash, MD, of the National Naval Medical Center in Bethesda, Md., and colleagues.

The investigators found colorectal neoplasia in 9.3 percent of cases and advanced neoplasia in 3.3 percent, while “potentially important” findings outside the colon were seen in 2.3 percent of patients, Cash and colleagues reported in the July issue of the American Journal of Roentgenology.

Taken together, the findings suggest that, contrary to a 2009 ruling by the Centers for Medicare and Medicaid Services (CMS), CT colonography screening is “a viable option for Medicare-aged patients,” the authors argued.

“Our study answers several of the questions Medicare asked about this procedure,” Cash said in a statement.

The agency ruled against paying for the non-invasive procedure, arguing that the evidence wasn’t good enough to qualify it as an appropriate screening test, largely because Medicare patients were either under-represented or excluded from trials.

To help clarify the issue, Cash and colleagues retrospectively analyzed outcomes for 1,410 consecutive Medicare-aged patients treated at the National Naval Medical Center, although 46 were excluded from the analysis because they underwent colonoscopy anyway as part of another research protocol.

Of those patients, they reported that 14.5 percent had either suspicious lesions or an inadequate CT exam and were referred to colonoscopy, and 14 percent actually had a colonoscopy.

There were no short- or long-term complications of either procedure.

Among the 198 patients with findings suggestive of colorectal disease, 129 had intermediate polyps, 67 had larger polyps and possibly advanced adenoma, and two patients had a colonic mass that was likely malignant.

Of the overall cohort, 131 patients (9.3 percent) had neoplasia and 46 had advanced neoplasia. The average size of the advanced lesions was 16.5 mm.

All told, 476 polyps or mass lesions were observed in the 14 percent of patients who went on to colonoscopy. Significantly more than half (60.7 percent) of the polyps were less than 6 mm while 25 percent were between 6 and 9 mm, and 14.3 percent were 10 mm or more.

The rates are “similar” to those seen in screening trials involving younger patients, Cash and colleagues noted.

The findings suggest that CT colonography “should be reconsidered” as an alternative screening test, they said, although they cautioned that the study was retrospective, so that not all possible confounding factors could be evaluated. Specifically, they did not know the percentage of patients in this analysis who had undergone previous colon cancer screening or polypectomy.

“A conservative estimate would be that at least 50 percent, based on Healthcare Effectiveness Data and Information Set compliance rates of our enrolled patient population,” they said.

The prevalence of colorectal neoplasia seen in this cohort may be less than what would be observed in a cohort of older patients without prior screening.

They argued the CT colonography should be “reconsidered for endorsement by both the [U.S. Preventive Services Task Force] and CMS.”