Colonoscopic surveillance using narrow-band imaging in patients with hyperplastic polyposis syndrome (HPS)

SUMMARY

Background and aim
Hyperplastic polyposis syndrome (HPS) is a condition in which multiple hyperplastic polyps (HPs) are spread throughout the colon. Patients with HPS are at increased risk of developing colorectal cancer (CRC) through a suggested HP-serrated adenoma (SA)-CRC pathway. While complete clearing of all polyps can sometimes prove difficult when multiple lesions exist, regular removal of at least all lesions with a possible risk, e.g. high-risk SAs, MPs and adenomas might adequately prevent the development of CRC. In this respect, endoscopic detection and differentiation of these polyps as well as adenomas is an important undertaking. However, the distinctive endoscopic appearance of SAs has never been described. Novel endoscopic techniques, like narrow-band imaging (NBI) may improve the endoscopic detection and differentiation of polyps in HPS. The aims of this study are to assess the additional value of NBI in comparison to white-light endoscopy (WLE) for the detection and classification of HPs, SAs, MPs and adenomas in patients with HPS.



Methods

Patients with HPS will be evaluated by colonoscopy using a prototype endoscopic imaging system which integrates WLE and NBI in one unit (Spectrum system, Olympus, Tokyo, Japan). All segments of the colon will be inspected twice, using both WLE and the NBI-mode in a randomized order. During the withdrawal phase, any lesion found will be classified according to macroscopic appearance. Size and localization will be recorded. Still images using white light and NBI will be taken and the lesion will be removed. In addition, the pit-pattern according to Kudo [4] will be scored using NBI. During the second withdrawal, after reintroduction to the beginning of the segment, these steps will be repeated using the other modality. The histopathological outcome of the biopsies will be used as the gold standard diagnosis.



Risk

The endoscopic procedure in this study is comparable to the standard procedure for regular patient care except that each segment of the colon will be inspected twice, which may lead to increasing the procedural time with about 15 minutes. Increasing the procedural time does not increase the risk of complications. The risk of a diagnostic colonoscopy is minimal (< 1‰).

Outcome

The sensitivity of WLE will be compared to that of NBI for the detection of polyps and cancer in the colon. The sensitivity of each technique will be calculated as the number of lesions detected during the first inspection, divided by the total number of lesions detected by both inspections. Furthermore, the surface pit pattern of the detected lesions on NBI will be used to obtain the overall accuracy (representing sensitivity and specificity) of this technique, by using the histological diagnosis as the gold standard diagnosis. Moreover, the prevalence and distribution of HPs, SAs, MPs and adenomas in this patient population will be described

The aims of this study are to assess the additional value of NBI in comparison to white-light endoscopy (WLE) for the detection and classification of HPs, SAs, MPs and adenomas in patients with HPS.

Inclusion: september 2007 - november 2008.

Data analysis: november-december 2008

Patients with HPS will be evaluated by colonoscopy using a prototype endoscopic imaging system which integrates WLE and NBI in one unit (Spectrum system, Olympus, Tokyo, Japan). All segments of the colon will be inspected twice, using both WLE and the NBI-mode in a randomized order. During the withdrawal phase, any lesion found will be classified according to macroscopic appearance. Size and localization will be recorded. Still images using white light and NBI will be taken and the lesion will be removed. In addition, the pit-pattern according to Kudo [4] will be scored using NBI. During the second withdrawal, after reintroduction to the beginning of the segment, these steps will be repeated using the other modality. The histopathological outcome of the biopsies will be used as the gold standard diagnosis.