CT Colonography Gets Another Look

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 - Colon

As colorectal cancer screening research marches on and options for screening continue to be evaluated, one constant remains: CT colonography is not covered by Medicare. However, some private payers cover the screening exam and this year it’s getting another look at the federal level. Where does CT colonography currently stand in the colorectal screening landscape?

This past summer, when the Centers for Medicare & Medicaid Services (CMS) approved Medicare coverage of a stool DNA colorectal cancer screening test, many in the imaging community were left wondering, “What about CT colonography?”

The DNA screening test was granted coverage under a new joint approval process with the FDA, but the American College of Radiology (ACR) drafted a letter to CMS arguing that CT colonography’s performance exceeds the standard applied to the DNA test.

“That [approval process] had not been available previously for CT colonography and it’s only for new techniques, so CT colonography is not eligible for that same route,” says Judy Yee, MD, chair of ACR’s Colon Cancer Committee and chief of radiology at the San Francisco VA Medical Center. Yee was the signed author of ACR’s letter to CMS.

One of the disappointing facets of seeing the DNA test approved in a joint process with the FDA is that CT colonography was already reviewed by the FDA in fall 2013. Yee notes that there was unanimous approval from the FDA Gastroenterology-Urology Devices Panel that CT colonography is safe and effective.

Approval of the DNA test while CT colonography remains in Medicare coverage limbo is just the latest chapter in the years’ long debate over whether Medicare beneficiaries should have the screening test covered. CIGNA, Anthem Blue Cross Blue Shield and a number of other payers currently cover screening CT colonography, but Medicare does not, and that could have a big impact on who is getting screened. While studies have shown that patients prefer CT colonography and would be more likely to go through with screening if it were an option (Am J Roentgenol. 2012 Jun;198:1361-6), most are not willing to pay out-of-pocket if insurance didn’t pick up the tab (Am J Roentgenol. 2010 Aug;195:393-7).

Multiple screening options, different purposes

Colorectal cancer screening guidelines from the American Cancer Society and ACR divide screening tools into two broad categories: those meant to identify cancer and those meant to prevent cancer.

The stool DNA test falls into the former group along with fecal immunochemical tests or the fecal occult blood test. These screening tools are not meant to prevent cancer, but instead are used to see whether a patient has it or not. “The intent of the stool DNA test is really to identify the cancer. It’s almost too late by then,” says Yee.

CT colonography, on the other hand, has high sensitivity for identifying precursor lesions that can be removed in order to prevent cancers. Other screening options that can help prevent cancer include colonoscopy and flexible sigmoidoscopy.

Perry Pickhardt, MD, professor in the Department of Radiology at the University of Wisconsin School of Medicine and Public Health, is a proponent of CT colonography and points out that not only is CT colonography more sensitive and specific for cancer than stool DNA, but it also can detect greater than 90 percent of advanced adenomas versus around 40 percent detection by stool DNA. He thinks any lingering concerns regarding CT colonography have already been answered. “CT colonography is clearly a good colorectal cancer screening test – perhaps the best of the available options. It is accurate, safe, fast, and convenient for patients.”

When asked what factors, then, are hindering more widespread adoption of CT colonography screening, Pickhardt says it’s mostly a lack of awareness, primarily among primary care providers. “Primary care physicians are largely late adopters of new technology.” He adds that the perceived “turf battle” with gastrointestinal specialists is another negative factor that can interfere with improved patient care and cost-effectiveness.

The endoscopic preventative screening methods do have their own advantages. Colonoscopy can save patients from having to go through multiple unpleasant bowel preparations since polyps can be removed during the initial exam if colonoscopy is used as the primary screening method. Large polyps discovered on CT colonography will often require a second procedure.

A recent Norwegian study of screening with one-time