Background and study aims: Recent data suggest that panchromoscopy using methylene blue can improve the detection of intraepithelial neoplastic lesions in the context of surveillance colonoscopy for patients with chronic ulcerative colitis. This method has also been shown to provide a more accurate diagnosis of the extent of disease and inflammatory activity. Interval cancers are known to occur in patients with chronic ulcerative colitis despite the adoption of currently accepted surveillance biopsy protocols. We hypothesised that targeted chromoscopy alone, with high-magnification imaging, may increase the total number of intraepithelial neoplastic lesions detected, compared with conventional colonoscopy and biopsy surveillance according to current protocols.
Patients and methods: A total of 350 patients with long-standing ulcerative colitis (>or=8 years) underwent surveillance colonoscopy using high-magnification chromoscopic colonoscopy (HMCC). Quadrantic biopsies at 10-cm intervals were taken on extubation in addition to targeted biopsies of abnormal mucosal areas. Defined lesions were further evaluated using modified Kudo crypt pattern analysis. These data were compared with data from 350 disease duration- and disease extent-matched control patients who had undergone conventional colonoscopic surveillance between January 2001 and April 2005.
Results: Significantly more intraepithelial neoplastic lesions were detected in the magnification chromoscopy group compared with controls (69 vs. 24, P<0.0001). Intraepithelial neoplasia was observed in 67 lesions, of which 53 (79%) were detected using magnification chromoscopy alone. Chromoscopy increased the number of flat lesions with intraepithelial neoplasia detected compared with controls (P<0.001). Twenty intraepithelial neoplastic lesions were detected from 12,850 non-targeted biopsies in the HMCC group (0.16%), while 49 intraepithelial neoplastic lesions were detected from the 644 targeted biopsies in the HMCC group (8%). From 12,482 non-targeted biopsies taken in the control group patients, 18 (0.14%) showed intraepithelial neoplasia. The yield of intraepithelial neoplastic lesions from targeted biopsies in the control group (i. e. without HMCC imaging), however, was only modestly improved at 1.6% (6/369). Using modified Kudo criteria, the sensitivity and specificity for differentiating neoplastic from non-neoplastic lesions using HMCC were 93% and 88% respectively. The total procedure time was significantly longer in the HMCC group compared with controls (P<0.02).
Conclusions: Magnification chromoscopy improves the detection of intraepithelial neoplasia in the endoscopic screening of patients with chronic ulcerative colitis. Neoplastic and non-neoplastic mucosal change can be predicted with a high overall accuracy using magnification techniques. These adjunctive endoscopic techniques have important clinical implications and may lead to changes in current practice guidelines.