Real-Time Endoscopic Assessment Of The Histology Of Diminutive Colorectal Polyps Examined By ASGE Initiative

Main Category: Colorectal Cancer
Also Included In: Medical Devices / Diagnostics
Article Date: 10 Mar 2011 - 0:00 PDT


In recognition of National Colorectal Cancer Awareness Month during March, GIE: Gastrointestinal Endoscopy has put out a special issue for March on colonoscopy and colorectal cancer. In this issue is the first statement from a new initiative by the American Society for Gastrointestinal Endoscopy (ASGE) called the Preservation and Incorporation of Valuable Endoscopic Innovations (PIVI). The first PIVI document examines real-time endoscopic assessment of the histology of diminutive (≤ 5 mm in size) colorectal polyps and is one in a series of statements defining the diagnostic or therapeutic threshold that must be met for a technique or device to become considered appropriate for incorporation into clinical practice. GIE: Gastrointestinal Endoscopy is the monthly peer-reviewed scientific journal of the American Society for Gastrointestinal Endoscopy (ASGE).

"In addition to defining thresholds for when a new technique or device is ready for use in clinical practice, PIVI statements are meant to serve as a guide for researchers or those seeking to develop technologies that are designed to improve digestive health outcomes," said M. Brian Fennerty, MD, FASGE, president, American Society for Gastrointestinal Endoscopy. "The purpose of the first PIVI is to focus efforts by clinicians and industry toward development of new paradigms for the colonoscopic management of diminutive polyps that minimize risk and unnecessary delay of information to patients while improving the cost effectiveness of colonoscopy. The PIVI's recommended thresholds for performance standards of technologies should serve investigators by establishing the correct group of target lesions in which to examine technologies that purport to allow real-time determination of histology, to create clinical endpoints in trials that are meaningful and relevant, and to estimate the required sample sizes for adequately powered studies."

Diminutive polyps are extremely common, with recent studies employing high definition colonoscopes identifying diminutive adenomas (precancerous polyps) in about half and diminutive polyps in more than half of the U.S. screening population. A much smaller fraction of the U.S. population develops colorectal cancer, and polyps larger than 5 mm in size are more likely than diminutive polyps to harbor cancer or advanced neoplasia, or to eventually develop into colorectal cancer. Current practice of colonoscopic management of diminutive polyps is generally to resect (remove) and submit them for pathologic assessment, however, the routine pathological assessment of all resected diminutive colorectal polyps results in substantial costs to patients and society for management of a group of lesions with limited clinical importance. Pathological assessment also causes a delay for informing patients of the histology of their polyps and in recommending the next colonoscopy surveillance interval.

The PIVI committee (consisting of a committee of ASGE physician experts) performed a literature review. Factors that were considered in reaching consensus regarding the recommended thresholds included the importance of the issue to clinical practice, the accuracy of the gold standard (pathology), and the impact of other factors that affect clinical outcomes. The PIVI is provided solely for educational and informational purposes and to support incorporating these endoscopic technologies into clinical practice. It should not be construed as establishing a legal standard of care.

PIVI Statements:

1. In order for colorectal polyps ≤ 5 mm in size to be resected and discarded without pathological assessment, endoscopic technology (when used with high confidence) used to determine histology of polyps ≤ 5 mm in size, when combined with the histopathologic assessment of polyps > 5 mm in size, should provide a ≥ 90 percent agreement in assignment of post-polypectomy surveillance intervals when compared to decisions based on pathology assessment of all identified polyps.
2. In order for a technology to be used to guide the decision to leave suspected rectosigmoid hyperplastic polyps ≤ 5 mm in size in place (without resection), the technology should provide ≥ 90 percent negative predictive value (when used with high confidence) for adenomatous histology.

"In addition to meeting these performance thresholds, other endpoints may need to be satisfied to establish that a technology can be used in the new paradigm in a manner that is feasible and accurate by community endoscopists," said PIVI Committee Chair Douglas K. Rex, MD, FASGE. "Technologies that meet the recommended thresholds specified in this PIVI, and which satisfy other necessary endpoints, will be supported by the ASGE, as well as other interested professional societies wishing to do so, as technologies that can be used to operate in this new paradigm and that the use of these technologies in meeting the new paradigm meets the standard of medical care for the management of diminutive colorectal polyps."

The PIVI statements rest on two general assumptions: First, all polyps in the proximal colon (proximal to the sigmoid colon) should be endoscopically resected, and all adenomas should be resected regardless of the location in the colon. Therefore to maximize the benefits of colonoscopy and polypectomy, the current paradigm of resecting all colorectal polyps except diminutive polyps in the rectosigmoid, which appear endoscopically to be hyperplastic (benign), should be preserved in the new paradigm; the second assumption is that there is a group of colorectal polyps that have a sufficiently low prevalence of advanced histology including cancer such that the only value offered by their pathological assessment is to guide assignment of the post-polypectomy surveillance interval. A detailed review of the literature indicates that polyps ≤ 5 mm in size have an extremely low prevalence of invasive cancer and a very low prevalence of advanced histology, and therefore constitute such a group of polyps.

The first new PIVI paradigm has been called the "resect and discard" strategy which could be appropriately applied to diminutive polyps anywhere in the colorectum. The histology of a diminutive polyp is assessed by an appropriate endoscopic method, the assessment is recorded by means of a high-resolution photograph, and then the polyp is resected. However, rather than submitting the polyp for pathologic assessment, the polyp is discarded and the endoscopic assessment of histology is used to determine the impact of the polyp on the patient's next post-polypectomy surveillance interval. The principal value in this paradigm is a reduction in costs for pathologic assessment of diminutive polyps. In many cases, the resect and discard paradigm allows an immediate recommendation regarding the next colonoscopy interval.

The second PIVI paradigm applies only to diminutive hyperplastic-appearing polyps in the rectosigmoid colon. It proposes that when multiple diminutive rectosigmoid hyperplastic polyps are suspected endoscopically, then the hyperplastic nature of these polyps can be established and documented by real-time endoscopic assessment and photography, without the need for sampling or resection of some or all of the polyps. The value of this second paradigm is a reduction in costs and risks associated with polypectomy, and a reduction in costs associated with pathologic assessment.

In many settings there may be a requirement that all resected tissue be sent for pathological assessment. The ASGE recommends that all state, local, and institutional rules be followed in this regard, but urges that appropriate channels be pursued to present the evidence and rationale for clinical goals addressed in this PIVI.

Source:
Anne Brownsey
American Society for Gastrointestinal Endoscopy

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