Diagnostics & Imaging Week Contributing Writer
CHICAGO – If you do the math, there will not be enough gastroenterologists to perform the required amount of colonoscopies to meet the national goal of screening 60% of everyone over 50 years of age for colorectal cancer (CRC).
Several possible solutions to assist with this problem were presented here at the Digestive Disease Week (DDW) annual meeting, along with a myriad of topics, all relevant to the alimentary tract.
DDW is a gathering of the four organizations that are exclusively focused on digestive diseases: the American Association for the Study of Liver Diseases (Alexandria, Virginia), the American Gastroenterological Association, (Bethesda, Maryland), the American Society for Gastrointestinal Endoscopy (Oak Brook, Illinois) and the Society for Surgery of the Alimentary Tract. (Beverly, Massachusetts).
Some 12 million colonoscopies are performed annually in the U.S., 70% of which are for screening. To meet the goal of screening 60% of Americans over 50, about 21 million screening colonoscopies would need to be performed – more than the current resources available.
A recurring theme presented at this year's DDW gathering was that of using optical diagnosis during the colonoscopy to increase throughput by eliminating unnecessary polyp removals and reducing the number of repeat colonoscopies.
"Optical diagnosis" includes a variety of modalities – high-definition white light as offered by Olympus (Center Valley, Pennsylvania), narrow band imaging, chromoendoscopy, or the newest entity: confocal microscopy – all of which enhance the standard view seen through an endoscope
The question becomes: can the image be equivalent to, or used in lieu of, a histologic examination of the polyp?
Optical diagnosis of small polyps at colonoscopy could provide several advantages for both patients and practitioners. If the number of polypectomies performed were reduced, there could be an increased efficiency for the procedure, both in time and cost. Patients would have less risk of bleeding or perforations, two complications that are rare but can occur. In an ideal world, the optical diagnosis may even be more accurate than histopathology.
Ana Ignatovic, of St. Mark's Hospital (London), presented "Optical Biopsy at Colonoscopy: Are We Ready? DISCARD Study: Early Results," where her team studied a method that may be more effective at examining and identifying polyps that are precancerous, thereby eliminating the time and expense of sending biopsies to pathology.
In a study presented at last year's DDW meeting, researchers demonstrated that the majority of polyps 9 mm or less were typically benign; yet under the current endoscopy protocol the majority of polyps removed during the procedure are less than 10 mm and are sent for pathology examination, which takes about a week for results.
In the study at St. Mark's, four endoscopists with varying degrees of experience used one or a combination of optical modalities to attempt to predict the histopathology of each polyp seen during the colonoscopy. Each polyp was then removed and sent for formal histopathology examination.
The researchers found that of the 85 benign adenomas removed, 92% were correctly diagnosed; and of the 38 hyperplastic polyps, 97% were accurately identified from optical diagnosis. In total, among all four endoscopists, of the 355 polyps removed, 270 were correctly identified by optical diagnosis.
Ignatovic, an endoscopy research fellow, concluded, "Optical diagnosis allows us to predict accurately whether a polyp should be removed immediately during the colonoscopy. This not only spares the patient the risk involved in the unnecessary removal of non-precancerous polyps, but also eliminates the wait time and expense involved in the current protocol of sending biopsies to pathology.
Optical diagnosis in vivo is feasible, comparable, quicker and cheaper than conventional biopsy protocol."
Taking optical diagnosis one step further than simply enhancing the endoscopic image, Cellvizio (Fort Washington, Pennsylvania) actually adds a probe-based tiny microscope to any endoscope, providing confocal laser endomicroscopy to any portion of the digestive tract. The world's most miniaturized microscope brings the power of a microscope in real time directly inside the body to evaluate any suspicious tissue.
While other optical enhancements such as HD white light and chromoendoscopy can detect, or red flag, suspicious areas, confocal microendoscopy can actually characterize the tissue. The goal is that with ongoing studies, to be able to eventually confirm the status of a polyp without a biopsy.
The Cellvizio system was developed by venture-backed Mauna Kea Technologies (Paris) and has received a 510(k) clearance from the FDA. It can also be used in the lung.
Until recently, a potentially diseased esophagus has been one of the more difficult areas to examine and/or treat endoscopically, mainly because the suspected diseases found there, such as Barrett's esophagus and esophageal varices (varicose veins), are vulnerable to bleeding.
While the prevalence of Barrett's esophagus is only 2% to 5% among the general adult population, it is between 5% and 10% for those with gastroesophageal reflux disease (GERD), the third-most-prevalent disease in the US.
Esophageal varices is found in about 50% of the 10 million Americans with cirrhosis, but standard endoscopy in these patients can become a prescription for disaster, with a great potential for bleeding. Both confocal microendoscopy and wireless camera endoscopy are less-invasive alternatives to standard endoscopy with biopsy.
The Pillcam ESO 2 by Given Imaging (Yokneam, Israel) is a small ingestible capsule the size of a large vitamin and is equipped with a miniature video camera and its own light source to visualize the esophagus. Data is transmitted to a recorder and the physician later reviews the compiled video data to make a diagnosis.
In a poster presentation by Neil Sharma, MD, of the division of digestive disease and nutrition at the University of South Florida (Tampa), he compared capsule endoscopy using Pillcam to standard upper endoscopy and concluded: "Detecting and monitoring varices is critical in this patient population. Requiring no sedation, esophageal capsule endoscopy provides a less-invasive but equally effective option for the screening of esophageal varices."
Although Given was the first to market with capsule endoscopy, other companies involved with the development of capsule endoscopes include Pentax (Montvale, New Jersey), Fujinon (Wayne, New Jersey), Olympus, Royal Philips Electronics (Best, the Netherlands), and Siemens (Malvern, Pennsylvania), and Innurvation (Columbia. Maryland).
The number of companies entering this space confirms the advantages and benefits of capsule endoscopy.
Researchers at Northwestern University (Evanston, Illinois) have pioneered a new method to screen for colon cancer through a minimally intrusive optical diagnostic test.
Herman Roy, MD, presented "Spectroscopic and Optical Signatures for Colorectal Cancer Screening," where he described the technology as a novel non-invasive optical light that shines inside the colon and analyzes how the reflected light interacts with the lining of the colon.
American BioOptics (also Evanston), a privately held company, has been formed around this technology to commercialize the company's, which can be highly accurate, office-based, require no bowel prep, and be inexpensive.
Roy said, "There are 90 million Americans over the age of 50 who should be screened for CRC, but most won't do it. We want to address those patients."