FUSE Outperforms Forward-viewing Colonoscopy in Detecting Dysplasia in Patients With IBD
The panoramic views obtained with full-spectrum endoscopy (FUSE) increase the number of dysplastic lesions detected in the colon, compared with conventional forward-viewing colonoscopy, researchers report in the May issue of Gastroenterology.
Inflammatory bowel diseases (IBDs) increase the risk of colorectal cancer. Surveillance colonoscopy with chromoendoscopy is recommended, but conventional forward-viewing colonoscopy detects dysplasia with low levels of sensitivity.
The full-spectrum, high-definition endoscope has camera lenses to the right and left sides of the colonoscope tip, in addition to the forward-viewing lens. These 3 lenses deliver a 330° panoramic field of view of the mucosa as opposed to the 170° field of view, compared with a conventional forward-viewing colonoscope. Improved visualization of the side walls, blind spots, and behind folds was reported to reduce adenoma miss rates from 41% to 7% in patients without inflammatory bowel diseases (IBD).
FUSE has not been evaluated in an IBD surveillance population. Colitis-associated dysplasia is more subtle than sporadic polyps, and flat dysplastic lesions located in the flexures and behind folds can be missed by conventional forward-viewing colonoscopes, even after dye-spray chromoendoscopy.
Rupert W. Leong et al performed a prospective study to determine whether FUSE reduces the numbers of dysplasias missed in patients with IBD undergoing surveillance colonoscopy compared with forward-viewing colonoscopy.
The authors compared forward-viewing colonoscopy with FUSE in 52 subjects with IBD undergoing surveillance for neoplasia in Australia. They were were assigned randomly to groups that underwent forward-viewing colonoscopy followed by FUSE, or FUSE followed by forward-viewing colonoscopy.
Random biopsy specimens were collected and visible lesions were collected; all were analyzed histologically. The primary end point was dysplasia missed by the first colonoscopy detected by the second colonoscopy.
First-pass forward-viewing colonoscopy missed 10 dysplastic lesions in 8 subjects. But among subjects who underwent FUSE first, 9 dysplastic lesions (including a flat intramucosal adenocarcinoma and 2 high-grade dysplastic lesions) were found in 6 subjects. First-pass FUSE missed 3 dysplastic lesions in 3 subjects.
The total colonoscopy times were similar (21.2 min for FUSE vs 19.1 min for forward-viewing), but withdrawal time was significantly longer for FUSE (15.8 min vs 12.0 min).
Correcting for per-unit withdrawal time, the mean dysplasia miss rate per subject was significantly lower for FUSE (0.19) than for forward-viewing colonoscopy. Targeted tissue acquisition identified significantly more dysplastic lesions than random biopsies.
The chance of missing subtle dysplasia during surveillance colonoscopy led to guidelines recommending that surveillance colonoscopies be performed as often as once per year for patients with IBD.
Yearly colonoscopy consumes resources, are costly to the health care system, and burdensome for patients. Leong et al state that FUSE increases the effectiveness of IBD surveillance and significantly decreases the dysplasia miss rate. Therefore, IBD surveillance procedures using FUSE with chromoendoscopy could lead to lengthening of colonoscopy surveillance intervals and provide patients and clinicians with greater reassurance of negative findings.
The Gastroenterology editors remind readers that this was a single-center study performed at a dedicated IBD unit. Although the endoscopists could not be blinded, the pathologists were blinded to the colonoscope allocation when interpreting resected specimens for dysplasia.