Relevant factors and significant endoscopic findings for detecting UC-associated neoplasms using pancolonic NBI surveillance colonoscopy: a sub-analysis of Navigator Study

BACKGROUND: We recently reported the results of a prospective multicenter randomised controlled trial comparing pancolonic observation using a newly developed NBI (CF-HQ290I) and panchromoendoscopy (PCE) for surveillance colonoscopy in UC patients. The results revealed that the NBI observation was not inferior to PCE for the detection of both neoplastic lesions (13.4% vs 9.0%; P=0.33) and colitis-associated dysplasia or cancer (CC/D) (6.3% vs 4.9%; P=0.86). Moreover, the total examination time of NBI (15.0 min) was significantly shorter than that of PCE (19.8 min) (P<0.01). This sub-analysis aimed to evaluate the relevant factors or NBI findings of the background mucosa of CC/D in the preceding Navigator Study (UMIN000013527).

METHODS: In total, 263 patients were randomised to the PCE group (n=130) and the NBI group (n=133). Surveillance colonoscopy in both groups was performed mainly with targeted biopsy. The pathological diagnoses were made by two expert pathologists who performed including immunohistochemical staining (p53, Ki-67) while being blinded to clinical information.

RESULTS: A total of 21 sporadic adenoma, 3 traditional serrated adenoma, 2 sessile serrated adenoma/polyp, 10 indefinite for dysplasia, 9 low grade dysplsisadysplasia, and 7 high grade dysplasia or cancer cases were detected. There was no statistical difference for in the contents of these detected lesions between the two groups (P=0.91). The median number of biopsy samples was not different between the two groups (1.80/case in NBI, 1.85/case in PCE; P=0.88). Multivariate analysis demonstrated that age (OR 1.05, 95% CI 1.02–1.08, P<0.01) and past history of CC/D (OR 4.26, 95% CI 1.29–14.05, P=0.02) were the relevant factors for the detection of neoplastic lesions, and past history of CC/D (OR 5.70, 95% CI 1.33–24.50, P=0.02) was the relevant factor for the detection of CC/D. CC/D was significantly more frequently detected than sporadic adenoma in cases in which the background mucosa had an obscure vascular pattern or scar rather than a fair view of the vascular pattern or out of range for inflammation (OR 25.0, 95% CI 3.80–164.4, P<0.01).

CONCLUSION(S): In the Navigator Study, a past history of endoscopic resection or detection of dysplasia on random biopsy was the relevant factor for the detection of CC/D. The NBI findings of the background mucosa were useful in differentiating CC/D and sporadic adenoma.