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24-Hour Summary: Office of the Commissioner Joint Meeting of the Gastroenterology-Urology Devices Panel and the Radiological Devices Panel

FDA Office of the Commissioner
Joint Meeting of the Gastroenterology-Urology Devices Panel
and the Radiological Devices Panel of the Medical Devices Advisory Committee
on Computed Tomography Colonography
September 9, 2013

Introduction

On September 9, 2013, the Office of the Commissioner convened a joint meeting of the Gastroenterology-Urology Devices Panel and the Radiological Devices Panel—both of the Medical Devices Advisory Committee—to discuss current evidence on the risks and benefits of computed tomography colonography (CTC) for the screening of asymptomatic patients for colorectal cancer (CRC).1   The meeting addressed particular matters of general applicability.  No conflict of interest waivers were needed.

Presentations

Seven experts presented aspects of the topic to the joint panels.2

  • Michael Pignone, MD, MPH, Professor, Internal Medicine, University of North Carolina-Chapel Hill, presented an overview of CRC and evidence on screening rates, the effectiveness of screening technologies other than CTC, and the impact of choice upon screening rates.
  • Duncan Barlow, MD, Department of Medicine, Uniformed Services University of the Health Sciences, presented an introduction to CTC and his institution’s experience using CTC in its Colon Health Initiative.
  • Perry Pickhardt, MD, Professor of Radiology, Chief of Gastrointestinal Imaging, University of Wisconsin-Madison, presented data from the Department of Defense CT Colonography Screening Trial.
  • Abraham Dachman, MD, Professor of Radiology, Department of Radiology, University of Chicago, presented data from the American College of Radiology Imaging Network (ACRIN) CT Colonography Trial.
  • Bernard Levin, MD, Professor Emeritus, University of Texas MD Anderson Cancer Center, presented an overview of federal, professional group, and private third-party payor guidelines on the use of CTC.
  • Amy Berrington de Gonzalez, DPhil, Senior Investigator, Division of Cancer Epidemiology and Genetics, National Cancer Institute, presented background on radiation risk, including that related to medical technologies, as well as evidence concerning the number of cancers prevented by CTC compared to the number induced by radiation.
  • Ronald Summers, MD, PhD, Senior Investigator, Radiology and Imaging Sciences, National Institutes of Health Clinical Center, presented on recent developments in CTC, including evidence on extracolonic findings, detection of lesions ≤ 9mm and flat polyps, effectiveness in the Medicare population, patient preferences, computer-assisted detection and other technical improvements.

Nine persons spoke at the Open Public Hearing, presenting the views of their organizations.  Please see the transcript for details.  FDA has opened a docket for written public comments.3

Questions and Discussion

All of the members of the joint panels agreed that, given the risks and benefits identified, CTC should be one option for CRC screening of asymptomatic patients.  The panel members reached this determination after considering the presentations by the invited speakers and in the Open Public Hearing, 20 papers provided to the panel prior to the meeting, and after deliberating on the specific questions FDA provided.  These questions are in bold below, followed by themes emerging from the joint panels’ discussion.

1. Considering available colorectal cancer screening tools and current colorectal cancer screening recommendations, please discuss the currently available data and information on:

  1. The potential benefits of CTC for the screening of asymptomatic patients for colorectal cancer, including test performance characteristics, impact upon overall numbers of patients screened and extracolonic findings.
    • There was general agreement that CTC provides benefit, and its sensitivity and specificity were adequate, at least for larger lesions.  Many members expressed the view that the effectiveness of CTC was comparable to optical colonoscopy (OC) for larger lesions. Some members commented that there were inadequate data on the clinical significance of smaller lesions.
    • Some members were concerned that the available data show effectiveness when used by experts and raised questions about how CTC would be applied in the community.  Others pointed out that the studies on OC were also conducted by experts, and that variable levels of expertise among the practitioners of OC was a well-recognized issue for OC effectiveness.
    • Many members emphasized the need for training physicians in performing and interpreting CTC.
    • There was discussion of data tending to show patient preference for CTC over OC. Some members questioned whether these data would translate to increased CRC screening, while others believed that the added choice was likely to attract new patients to screening.
    • Many members commented that an additional option for screening is a benefit, and that CTC is sufficiently sensitive and specific to be counted as such an option, though members noted the need for further information in several areas.
    • Some members expressed concern that CTC might miss flat lesions. Others noted that missing flat lesions was also an issue for OC.
    • Some members highlighted specific benefits of CTC compared to OC, such as the speed of the procedure, lack of sedation, and the ability to drive and return to work the day of the procedure.  On the other hand, any suspicious lesions encountered on CTC require referral to OC for excision.
  2. Safety issues related to the use of CTC for the screening of asymptomatic patients for colorectal cancer, including radiation risk and extracolonic findings.
    • Several members emphasized that the overall radiation risk of CTC is low, particularly when used in patients over 50.  Some members said that doses were lower now than in the past and that estimates of risk in prior publications had been based upon higher exposure estimates.
    • Some members commented that the benefits of increasing the screening pool outweigh the risk of additional exposure to radiation.
    • Some members commented that the risks of OC, including the risk of perforation, are substantially greater than the small radiation risk from CTC. 
    • Several comments highlighted a lower risk of perforations in CTC compared to OC. 
    • Views were mixed about the impact of extracolonic findings on overall safety and benefit.  Some regarded extracolonic findings as a benefit of CTC and others as a risk for unnecessary procedures, though some said that risk was small. Several members said there was a need for more data on this question.
    • Some stated that the frequency of CTC (every five years) compared to OC (every ten years) provided some margin of safety if smaller lesions were missed on CTC.  One member commented that the less frequent need for OC screening might make patients prefer OC.
    • Members were concerned about adherence with the CTC screening protocol and noted general lack of information about patient follow-through with recommendations for repeated CTC screenings.

2. Given the risks and benefits identified, please discuss your views on the role of CTC as one option for screening asymptomatic patients for colorectal cancer.

  • Members unanimously agreed that CTC should be available as an option for CRC screening of asymptomatic patients.
  • Many members strongly stressed the importance of training the practitioners of CTC and holding facilities accountable, and some suggested that the Mammography Quality Standards Act could be a model for CTC quality.  Several commented further that the facility should be certified, but that the practitioner would not necessarily have to be a radiologist, if adequately trained.
  • Some members noted that CTC should not be indicated for younger patients who are at higher radiation-induced cancer risk and for whom screening benefits are lower.
  • Some commented that, while CTC should be an option for CRC screening, because OC is therapeutic as well as diagnostic, OC should be recommended as the first choice.
  • Some remarked that CTC would be particularly appropriate for patients who could not tolerate or who had contraindications to OC.

Footnotes

1. An Executive Summary and bibliography of scientific literature were distributed before the meeting.

2. See the meeting information webpage for the presentations of all the guest speakers, and also see the transcript for full text of their remarks.

3. For comments filed to the docket, see FDA-2013-N-0816 at http://www.regulations.gov