Narrow band imaging for colonoscopic surveillance in hereditary non-polyposis colorectal cancer

Colonoscopic surveillance for hereditary non-polyposis 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.

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.

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% CI 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.

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