I just came back from the AMA CPT meeting, where dozens of topics are debated "pro and con" with opposing stakeholders.
I was reminded that I attended the 2008 CMS MEDCAC on whether to cover screening CT colonography (aka "virtual colonscopy.") My memory is that the numerous radiology speakers were strongly in favor, and the service had big public health benefits. And the numerous gastroenterology speakers were highly concerned the data were premature and many risks were too poorly understood and coverage would be a bad, bad idea.
Find the 2008 MEDCAC webpage here. The 2009 NCD is here.
- Follow up. CT colography became a covered screening benefit in January 2025, based on regulatory changes in 2024 rulemaking for PFS CY2025 - here.
Below, I fed the transcript and speaker list to Chat GPT and asked for a review. It produced the review below in less than 30 seconds.
After the read-out from Chat GPT 5.2, I asked it to write an essay about the day as a case study. I print the case study first, and the (earlier) AI analysis second.
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A Case Study in Interpretive Pluralism:
CT Colonography, Medicare, and the Social Life of Evidence
When historians of health policy look back at Medicare’s long and circuitous path toward covering CT colonography (CTC) for colorectal cancer screening, they may be tempted to frame it as a simple story of “evidence catching up with policy.” That narrative would be comforting—and largely wrong. The more instructive reading is that this episode reveals how the same empirical record can support sharply divergent conclusions, depending on professional identity, institutional incentives, and rhetorical framing. CT colonography is not merely a story about imaging technology; it is a case study in how evidence-based medicine operates in the real world, where evidence is interpreted, not discovered, and where policy decisions are forged through persuasion as much as data.
From the standpoint of raw evidence, the CT colonography literature circa the late 2000s was neither thin nor obviously defective. Large multicenter trials existed. Sensitivity for large adenomas and cancers approached that of optical colonoscopy under controlled conditions. Complication rates were demonstrably lower. Modeling studies suggested population-level benefits if screening adherence increased. Yet these same facts were marshaled to argue for coverage, non-coverage, and coverage-with-evidence-development, depending on who was speaking. This divergence was not accidental, nor was it merely cynical. It reflected different professional priors about what constitutes “sufficient” evidence, what risks matter most, and which uncertainties are tolerable in public programs.
Radiology-aligned stakeholders interpreted the evidence through a population-health and access lens. To them, CT colonography was a screening test, not a therapeutic intervention, and its value lay less in per-lesion perfection than in its ability to bring unscreened patients into the system. Missed small adenomas were contextualized against the known miss rates of optical colonoscopy itself. Radiation exposure was reframed as negligible in an older population. Extracolonic findings—often criticized as a source of downstream cost—were rhetorically repositioned as serendipitous early diagnoses. In this telling, the evidence demonstrated that CTC was “good enough,” safe enough, and mature enough to merit coverage now, with quality standards layered on over time.
Gastroenterology and endoscopy stakeholders looked at the same studies and reached nearly opposite conclusions. Their interpretive frame was clinical pathway integrity. From this perspective, uncertainty about the natural history of small polyps was not a minor gap but a central flaw. A screening modality that deferred or fragmented definitive intervention was seen as destabilizing rather than enabling. Referral thresholds, follow-up adherence, and the risk of false reassurance loomed large. Even extracolonic findings, celebrated by radiologists, were cast as potential sources of overdiagnosis and patient harm. Importantly, many GI leaders did not deny the technical performance of CT colonography; rather, they argued that the evidence base was insufficient to justify routine coverage in a national program without further real-world data. Hence the appeal of Coverage with Evidence Development—not as an endorsement, but as a brake.
What makes this episode especially instructive is that both sides were practicing evidence-based medicine, at least as they understood it. Each group emphasized different endpoints, different harms, and different definitions of benefit. Neither side fabricated data. Neither side ignored uncertainty. Instead, they weighted uncertainty differently. This should unsettle any naïve belief that evidence, once generated, speaks for itself. In practice, evidence is always filtered through professional norms about acceptable risk, clinical responsibility, and the moral obligations of a specialty to its patients.
The eventual shift in Medicare policy—decades after the original MEDCAC debate—did not occur because one side was finally “proven wrong.” Rather, it reflected changes in context: improved technology, broader acceptance of non-invasive screening, political attention to preventive care, and sustained rhetorical work by advocates who reframed CTC as complementary rather than competitive. Congress did not suddenly resolve the epistemic dispute; CMS reinterpreted the same general evidentiary landscape under new policy priorities.
The lesson here is not that all interpretations are equally valid, nor that expertise is illusory. It is that no single stakeholder group has a monopoly on correct interpretation, especially in areas where evidence is probabilistic, outcomes are long-term, and implementation matters as much as efficacy. Health policy is not physics. Facts and numbers do not announce their meaning independently of human judgment. They acquire meaning through argument, narrative, and institutional context.
For students of Medicare policy and evidence-based medicine, CT colonography offers a durable warning against epistemic arrogance. Advisory committees are not courts of law where evidence is weighed once and for all; they are arenas where professional cultures collide. Rhetoric—far from being the enemy of science—is the medium through which scientific claims are made legible to policymakers. The challenge is not to eliminate rhetoric, but to recognize it, interrogate it, and understand whose values it encodes.
In the end, the CT colonography story teaches us intellectual humility. Policy decisions emerge not from the triumph of facts over politics, but from negotiated interpretations of uncertain evidence. To take any one side too seriously—to believe that the numbers alone compel a single conclusion—is to misunderstand how medicine, policy, and human judgment actually work.
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Chat GPT analysis of transcript (it did this first, and wrote the essay above second.)
Executive takeaway: Colography Transcript as Data
Radiology-aligned speakers and imaging manufacturers were uniformly supportive of Medicare coverage for CT colonography, while most gastroenterology and endoscopy society representatives opposed routine coverage or sought to sharply constrain it—often proposing Coverage with Evidence Development (CED) as a limiting compromise.
This MEDCAC is one of the clearest specialty-split advisory records CMS ever produced.
Categorization by speaker
Radiology & Imaging Industry — Supportive of Coverage
These speakers explicitly urged CMS to cover CT colonography or framed it as a mature, mainstream screening alternative.
Dr. Mark Klein (Radiology)
Strongly pro-coverage. He reframed extracolonic findings as a benefit rather than a harm, dismissed radiation risk as irrelevant in a Medicare population, and emphasized training and quality standards rather than restriction.
Dr. Charles (Dan) Johnson (Mayo Clinic / ACR)
Pro-coverage. Presented ACRIN trial results as validation of CT colonography, stressed reader training and technical maturity, and spoke explicitly on behalf of the American College of Radiology.
Dr. J.G. Fletcher (Mayo Clinic / ACR)
Pro-coverage. Focused on increased screening adherence and argued that CT colonography could improve population-level effectiveness.
Dr. Beth McFarland (ACR)
Pro-coverage. Supported accreditation, standards, and inclusion of CT colonography within Medicare screening options.
Dr. Donald Rucker (Siemens)
Strongly pro-coverage. Actively minimized radiation risk and argued that the benefit–risk balance overwhelmingly favored CT colonography in Medicare beneficiaries.
Dr. Robert Honinberg (GE Healthcare)
Strongly pro-coverage. Explicitly urged CMS to include CT colonography as a covered screening option, emphasizing technological maturity and NIH-validated evidence.
Gastroenterology & Endoscopy — Opposed or Restrictive
No gastroenterology society speaker endorsed straightforward national coverage.
Dr. Jason Dominitz (ASGE)
Opposed to routine coverage. Emphasized uncertainty in the management of small polyps, raised concerns about follow-up adherence and downstream harms, and did not endorse CT colonography as a screening substitute.
Dr. Douglas Rex (ACG)
Opposed or highly skeptical. Focused on false positives, downstream colonoscopy burden, and concerns about missed lesions relative to the endoscopic standard of care.
Dr. Brooks Cash (Navy / AGA)
Restrictive and skeptical. Highlighted uncertainty in clinical pathways and emphasized GI-centric quality and performance concerns.
Dr. Joel Brill (American Gastroenterological Association)
Conditional and restrictive. This is the key nuance. The AGA did not support routine coverage and instead proposed Coverage with Evidence Development, framing CT colonography as promising but not ready for unrestricted Medicare screening. In practical CMS terms, this functioned as a containment strategy rather than endorsement.
Dr. Amy Patrick (Colon Health Center)
Skeptical. Focused on unresolved clinical uncertainties and downstream consequences, without advocating coverage.
Dr. Robert Smith (American Cancer Society)
Cautious and non-endorsing. Reflected ACS’s neutral-to-skeptical position at the time and did not press CMS for coverage.
The pattern you remembered — confirmed
The MEDCAC record shows a stark and consistent divide:
Radiology framed CT colonography as a technologically mature, patient-friendly screening modality that could expand access and compliance, minimized harms, and portrayed extracolonic findings as an added benefit.
Gastroenterology framed CT colonography as clinically destabilizing, insufficiently validated in real-world practice, and threatening to established endoscopic pathways—using uncertainty and calls for CED as structural brakes on adoption.
This was not a subtle disagreement. It was a classic specialty turf conflict, expressed through evidentiary and patient-safety rhetoric.
Why this MEDCAC still matters
This meeting remains a canonical example inside CMS of how:
“Reasonable and necessary” determinations are shaped by specialty politics as much as evidence
Advisory panels surface professional boundary disputes under the guise of uncertainty
Coverage with Evidence Development can operate as de facto non-coverage
Your recollection aligns extremely closely with the documentary record.
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Bonus
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How would you explain this course of events, to a third-grader?
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How Two Kinds of Doctors Look at the Same Facts and Disagree
Imagine two people looking at the same set of facts, like a picture or a chart.
One says,
“This shows a good way to help more people.”
The other says,
“This shows something we shouldn’t use yet.”
The facts didn’t change.
What changed is what each person cares about most.
That’s what happened with these two kinds of doctors.
The Two Groups
Radiology doctors use imaging machines to find problems.
Gastroenterology doctors use scopes to look directly inside the colon and fix problems right away.
Both want to prevent cancer.
They just do different jobs, so they focus on different risks.
The Same Data, Different Questions
The data said:
The test finds many cancers
It’s safer and easier for patients
It might miss very small problems
It doesn’t treat anything directly
Those facts don’t tell you what to do.
They wait for someone to decide which of them matters most.
How Each Group Interprets the Data
Radiology doctors ask:
“Will this help more people get screened at all?”
They worry most about people who never get tested.
To them, a test that is “good enough” and easier to accept can save more lives.
Gastroenterology doctors ask:
“Will this ever delay or miss something important?”
They worry most about certainty and follow-through.
To them, a test that doesn’t diagnose and treat in one step feels risky.
Why This Isn’t About Right vs. Wrong
No one changed the facts.
No one ignored the evidence.
Each group:
Weighted the risks differently
Focused on different harms
Defined “good medicine” in different ways
That’s why the same data led to opposite conclusions.
What We Learn From This
This case teaches a simple but uncomfortable lesson:
Facts and numbers don’t speak for themselves. People speak for them.
Professional roles, daily experience, and values shape how evidence is understood.
That doesn’t mean anyone is acting in bad faith — it means medicine is human.
If we remember that, we’re less likely to assume one side has a monopoly on truth, and more likely to understand why disagreement can be sincere, informed, and inevitable.
