ACR Bulletin

Covering topics relevant to the practice of radiology

CT Colonography: A Policy Impasse, or Opportunity?

The ACP now says CTC shouldn’t be used for primary colon cancer screening. USPSTF recommends CTC. Commercial carriers pay for it, but Medicare doesn’t. Why the conflicting policies, and what can the Neiman Health Policy Institute do to help?

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Elizabeth Rula

Elizabeth Rula
Executive Director
Harvey L. Neiman Policy Institute®

October 02, 2023

Colon cancer screening is a rite of passage that most 45-year-olds dread far more than the mammograms women started getting a few years earlier. If you consider classic decision-making schemes — i.e., risk vs. reward, cost vs. benefit, effort vs. impact — it can be difficult to make the traditional colonoscopy’s equation work and, accordingly, adherence is only about 60%.1

As a result, multiple new less invasive or onerous options have emerged as FDA-approved screening methods, including stool-based tests and CT colonography (CTC), also known as virtual colonoscopy. But CTC has faced a difficult path despite a strong base of supporting evidence, and it recently hit a new roadblock when the American College of Physicians (ACP) did not include it among its recommended options for colon cancer screening, despite the fact that the U.S. Preventive Services Task Force (USPSTF) has included CTC in its recommendations since 2016.2,3 

Although optical colonoscopy clinically remains the gold standard for colon cancer screening because of its high sensitivity for detecting smaller polyps and the concurrent opportunity it provides to remove any pre-cancerous polyps in the colon, many patients still avoid or delay a colonoscopy. The avoidance is often due to the risk of perforation or bleeding, the requirement to take a full day off work to handle the anesthesia, and the need to find someone to drive you home. Is it worth the risk and cost in terms of time, productivity and perhaps wages? 

It is understandable that there is confusion regarding which screening technique is better, and even why optical colonoscopy remains the uncontested gold standard, because the comparison isn’t a simple one.

The value of screening for colorectal cancer is clear. Colon cancer is among the top five cancers in the U.S. At least one in 25 people will develop colorectal cancer in their lifetime, but this disease can be cured 90% of the time if the cancer is found early.4 Consider that perhaps the screening method people are willing to adhere to may be the best method, even if there is a slight tradeoff for the factors patients find beneficial.

For example, CTC takes only about 15 minutes, is non-invasive and doesn’t require down time due to anesthesia. CTC is also comparably sensitive and specific to colonoscopy, although there is associated radiation and polyps cannot be removed.5 While this latter tradeoff is often cited as a reason to discount the value of CTC, the data show that about 75% of colonoscopies do not identify any polyps for removal. Additionally, there is also a very small but real added risk of perforation of the colon whenever polyp removal is performed during colonoscopy.

It is understandable that there is confusion regarding which screening technique is better, and even why optical colonoscopy remains the uncontested gold standard, because the comparison isn’t a simple one. While CTC is widely accepted to have diagnostic accuracy comparable to optical colonoscopy for larger polyps, it may miss diminutive polyps that are less than 5 mm. But such diminutive polyps are rarely pre-cancerous (high-grade dysplasia), much less malignant, and it has been debated whether they should even be reported.

On the other hand, CTC has several important clinical advantages compared to colonoscopy. In addition to the risk of acute complications with colonoscopy because of its invasive nature, a lesser-known downside is that 10% to 15% of these screening exams fail to be completed for a variety of reasons, including abnormal colonic shape or size. CTC, however, can visualize the entire colon and is performed in follow-up to an incomplete colonoscopy to view the remainder of the colon. It is also able to detect cancers outside of the lumen of the colon. In the case that screening identifies a cancerous lesion, CTC has the advantage of pinpointing the exact location of the tumor for surgical planning and can identify any enlarged nodes.

Another issue that cannot be ignored as we consider screening options is the pervasive disparities observed for colorectal cancer. Death rates are 47% higher in Black men and 34% higher in Black women compared to White men and women.6 About one-fifth of this racial disparity has been attributed to lower screening rates.7 But CTC as a screening option may be starting to narrow this disparity. Recent data from the National Health Interview Survey found that more Black and Latinx people are getting screened with CTC compared to Whites. But do all patients have equal opportunity to choose CTC versus optical colonoscopy?8,9

Ironically, screening CTC is covered in full by most private insurers but is NOT covered by Medicare. This difference exists because the Affordable Care Act mandates commercial coverage of CTC as a USPSTF-recommended screening strategy, but this mandate does not apply to Medicare. Now CTC is covered by nearly all commercial insurance plans. This paradoxical situation caused the ACR staff economics team to ask the research team at the Neiman HPI to see how often Medicare patients are undergoing CTC, despite the fact that they have to pay out of pocket for 100% of the cost.

When we analyzed the Medicare data, we were very surprised by the extent to which Medicare beneficiaries still opt for CTC. Consequently, we decided to study which patients were choosing CTC, because surely paying out-of-pocket for the screening when a colonoscopy is free of cost to the patient is not a reasonable option for everyone. Joining us on this important effort were colorectal cancer screening experts, including Judy Yee, MD, FACR, chair of the ACR Colon Cancer Committee and chair of radiology at Montefiore Medical Center in the Bronx, who helped develop CTC; Courtney C. Moreno, MD, and Kevin J. Chang, MD, FACR, members of the ACR Colon Cancer Committee, as well as Mayo Clinic gastroenterologist David Bruining, MD.

Using Medicare claims data from 2011 through 2020, our study evaluated colorectal cancer screening among 2.4 million beneficiaries relative to income (using ZIP code per capita income), race/ethnicity and urbanicity. Our results showed that income of a patient’s community was an important determinant of whether that person was screened by CTC. Beneficiaries living in the highest-income areas (at or above $100,000 a year) were 5.7 times more likely to have a CTC screening compared with those in the lowest-income group, below $25,000.

Medicare-covered screening methods did not evidence such large income disparities. For colonoscopy, the highest-income group had a 36% higher likelihood relative to the lowest-income group, which, while significant, isn’t in the same ballpark as the analogous 573% higher likelihood for CTC.10

According to Eric Christensen, PhD, Neiman HPI director of research and lead study author, “an interesting finding was that, despite the wide income disparity observed for CTC, no significant racial or ethnic disparity was observed. This finding is congruent with outside evidence that minority groups may seek alternatives to optical colonoscopy, at least when they can afford to do so.”11,12

As scientists, we try our hardest to poke holes in our own results and conclusions. One potential gap in this study that we further explored is whether differences existed in a patient’s access to CTC versus colonoscopy. Our clinical experts suggested a clever approach to rule out this possibility by comparing it to diagnostic CTC, a test fully covered by Medicare, which showed a much smaller income disparity despite the fact that geographic/community access is necessarily identical given that they require the same equipment and radiologist specialization.

ACR advocacy initiatives are using these data to make a case that Medicare’s lack of coverage for CTC is preventing growth in colorectal cancer screening that can save many lives. Furthermore, this policy decision does not affect all Medicare patients equally. Those who prefer CTC and have the means are still getting screened. Unfortunately, about 50% of adults 65 and older have income less than $27,382 from all sources, according to the Pension Policy Center.13 It’s this large proportion of beneficiaries from lower socioeconomic groups who do not have expendable income who are affected because many aren’t being screened at all.

According to Yee, ACP’s recent exclusion of CTC as a primary tool for colon cancer screening and recommendation that screening starts at age 50 rather than at age 45 will have negative effects on the intended goal of increasing screening for this largely preventable cancer. “This is causing unnecessary confusion for clinicians and patients as major organizations including the USPSTF and the American Cancer Society support CTC as an accurate and safe test for colon cancer screening and they have changed their guidelines to start screening at age 45," Yee says. "We need to stop the confusion. The best screening test is the one that actually gets done.”

What about the cost of these procedures, you may ask? One may assume that CTC is more expensive, and that’s why Medicare won’t cover it. NO! In fact, CTC costs less than one-third that of colonoscopy.14,15 We must acknowledge that a subset of patients with positive findings on their CTC will require a colonoscopy in follow-up — 12% for Medicare-age patients, according to C-RADS guidelines — so the lower cost for a majority of patients more than covers the increased cost for the minority that require subsequent colonoscopy.16 This simple logic is supported by numerous studies that uniformly support CTC as a cost-effective screening strategy.17,18,19,20

All of this information begs the question, What evidence does CMS require? We wish we had a crystal ball to answer that question or that CMS would provide requirements similar to the standards all the other colorectal cancer screening tests are held to.

The evidence in support of CTC is already strong. CMS is heavily focused on health equity, and we hope our recent study has the potential to move the needle forward given the identified income disparities. We have more work underway under the leadership of Pina C. Sanelli, MD, MPH, at the Neiman Institute PRIME Center at Northwell Health focused on assessing the cost-effectiveness of colorectal cancer screening strategies.

According to Sanelli, “This research intends to fill the remaining evidence gaps so that Medicare may have the evidence they require to ensure coverage that may increase screening in at-risk communities and improve outcomes equitably.”

To learn more about our study, visit the Neiman HPI Press Center.