Abstract

Background: Colonoscopic surveillance for hereditary nonpolyposis colorectal cancer (HNPCC) reduces death rates but early interval cancers still occur, probably due to missed small, aggressive adenomas. Narrow band imaging (NBI), a novel endoscopic technology, highlights superficial mucosal capillaries and improves contrast for adenomas. This study examined whether a second pass with NBI in the proximal colon helped detect additional adenomas in patients with HNPCC.

Methods: 62 patients from HNPCC families (Amsterdam II or genetic criteria) attending for colonoscopic surveillance were examined twice from caecum to sigmoid-descending junction, first with high definition white light and then a second pass with NBI in a back-to-back fashion. All polyps detected were removed for histopathological analysis.

Results: At least one adenoma in the proximal colon was detected during the initial white light pass in 17/62(27%). NBI detected additional adenomas in 17/62(27%). 26/62(42%) patients had at least one adenoma detected after both white light and NBI, absolute difference 15% (95% confidence interval 4-25%), P=0.004 versus white light alone. The total number of adenomas increased from 25 before NBI to 46 after NBI examination, P<0.001. The proportion of flat adenomas detected in the NBI pass, 9/21(45%) was higher than in the white light pass 3/25(12%), P=0.03. Including white light examination of the sigmoid and rectum, overall 28/62(45%) patients had at least one adenoma detected.

Conclusions: Use of NBI in the proximal colon for patients undergoing surveillance HNPCC appears to improve adenoma detection, particularly those with a flat morphology. NBI could help reduce interval cancer rates. ClinicalTrials.gov Identifier:NCT00313755