Chromoendoscopy urged as standard of care in surveillance colonoscopy
Patients with inflammatory bowel disease (IBD) have a higher risk of colorectal cancer (CRC), which increases with the duration, extent and severity of inflammation. The standard of care for these patients calls for colonoscopic surveillance with random mucosal biopsies to detect early dysplasia. But this method not only is time-consuming and expensive, it is also inefficient — the random biopsy yield for dysplasia is just 0 to 0.2 percent.
Chromoendoscopy (CE) — the spray application of dye to the colonic mucosa — can improve dysplasia detection rates fourfold in ulcerative colitis (UC) and Crohn's disease compared with random biopsy sampling. CE is also superior to other imaging modalities, including narrow band imaging, in differentiating between neoplastic and non-neoplastic changes and diagnosing the extent and inflammatory activity of disease. Thus, CE is now recommended for colitis surveillance by the Crohn's and Colitis Foundation of America and the American Gastroenterological Association.
Despite growing enthusiasm, however, chromoendoscopy has remained controversial and difficult to implement in clinical practice. Perceived barriers include the lack of endoscopist experience, reliability of image interpretation, cost and additional time needed to perform the procedure. To address these concerns, Michael F. Picco, M.D., chair of the Division of Gastroenterology and Hepatology at Mayo Clinic's campus in Jacksonville, Florida, and colleagues studied whether CE could be easily implemented across three Mayo Clinic sites.
For the study, they recruited six endoscopists from Mayo Clinic campuses in Arizona, Florida and Minnesota. The endoscopists, who were inexperienced with chromoendoscopy, underwent a short training session that consisted of viewing a teaching file of images and instruction in CE. They then performed surveillance colonoscopy with white light endoscopy (WLE) followed by CE on 75 patients with long-standing ulcerative colitis.
All polypoid abnormalities were photographed and biopsied in each phase of the procedure; endoscopically normal areas were also photographed and randomly biopsied. The withdrawal time from the cecum was recorded for combined WLE visualization, standard surveillance biopsies, indigo carmine staining and inspection.
The results, published in Inflammatory Bowel Diseases in 2013, showed excellent interobserver agreement for both WLE and CE images. Dysplasia detection rates with CE were superior to those with WLE, especially for flat lesions. And though withdrawal times were initially long and variable, they decreased with experience, ranging from 31 minutes for fewer than five procedures to 19 minutes for 15 completed procedures or more. In other studies involving tandem biopsies — WLE followed by indigo carmine staining — overall withdrawal time was 21 minutes, similar to Mayo's experience.
"We showed that with minimal training, an individual can become competent after 15 procedures," Dr. Picco points out. He also observes that replacing random biopsies with directed CE biopsies would likely reduce procedure time as well as costs.
"If you are proficient at chromoendoscopy, the yield for dysplasia is four times higher than for standard colonoscopy. It is my hope that in the future the practice of obtaining random biopsies can be abandoned if chromoendoscopy is performed. If you don't perform random biopsies, then the time for chromoendoscopy is very similar to that for standard surveillance," he says. "No one has done a cost analysis, but my contention is that if you aren't doing random biopsies, then what you are biopsying is probably cost-effective."
Dr. Picco believes chromoendoscopy should be the standard of care, despite objections by the American College of Gastroenterology and others who lack of knowledge of the natural history of the lesions identified by CE and raises questions about its benefits. "It's true we don't know the natural history of some of the small lesions discovered with chromoendoscopy, but I think finding more polyps will translate into better outcomes," he explains.
Dr. Picco and colleagues outlined the key steps for implementing CE into solo and group practices in an article (see Table 1) that appeared in Gastrointestinal Endoscopy Clinics of North America in 2014.
For more information
Picco MF, et al. Procedure time and the determination of polypoid abnormalities with experience: Implementation of a chromoendoscopy program for surveillance colonoscopy for ulcerative colitis. Inflammatory Bowel Diseases. 2013;19:1913.
Leong RW, et al. Implementation of image-enhanced endoscopy into solo and group practices for dysplasia detection in Crohn's disease and ulcerative colitis. Gastrointestinal Endoscopy Clinics of North America. 2014;24:419.