Fecal calprotectin testing can identify ineffective colorectal cancer surveillance procedures in patients with longstanding colitis

Abstract

Background: Active colitis impairs neoplasia detection during colonoscopic surveillance for colorectal cancer in patients with inflammatory bowel disease. We investigated whether fecal calprotectin testing before surveillance colonoscopy might identify ineffective surveillance procedures. Methods: All consecutive patients with Crohn's disease or ulcerative colitis scheduled for surveillance colonoscopy were asked to collect a stool sample before the start of bowel cleansing. Ineffective surveillance was defined as at least 1 colonic segment with moderate or severe inflammation. Calprotectin was analyzed using an enzyme-linked immunosorbent assay (Ridascreen; R-Biopharm). Receiver operator characteristics statistics were used to determine the optimal cutoff for calprotectin. Results: A total of 176 surveillance colonoscopies were performed in 164 patients, of which 83 had Crohn's disease and 81 had ulcerative colitis or inflammatory bowel disease-unclassified. Complete endoscopic remission or mild inflammation categorized as effective surveillance was observed in 151 colonoscopies (86%), whereas moderate or severe inflammation categorized as ineffective surveillance was observed in 25 colonoscopies (14%). Median calprotectin levels for the effective and ineffective surveillance group were 84 mg/kg (range, 20-4609) and 1605 mg/kg (range, 66-26,336), respectively (P < 0.01). A cutoff of 539 mg/kg identified patients with ineffective surveillance with 84% sensitivity, 89% specificity, 55% positive predictive value, 97% negative predictive value, and an area under the curve of 0.89. Conclusions: Low fecal calprotectin accurately identifies inflammatory bowel disease patients without colonic inflammation in whom colorectal cancer surveillance is most effective. Copyright © 2014 Crohn's & Colitis Foundation of America, Inc.