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Narrow Band Imaging

Brian Saunders, MD FRCP

The purpose of this study is to determine whether a new colonoscopic viewing technique called narrow band imaging (NBI)can help doctors detect more patients with at least one pre-cancerous area than conventional colonoscopy using white light alone in patients with genetically inherited high risk for bowel cancer (HNPCC).

Colorectal cancer is the second commonest cause of cancer death. Some people have an inherited defect in the genes which repair DNA which results in a very high risk of colorectal (bowel) cancer at a young age. This syndrome is called hereditary non-polyposis colorectal cancer (HNPCC) or Lynch syndrome. Colonoscopic surveillance of HNPCC patients has been shown to reduce the risk of colorectal cancer and allow detection at an earlier stage, but even with meticulous examination, some precancerous lesions or cancers are missed.

Precancerous lesions in HNPCC are difficult to see and may be advanced even if as small as a few millimeters. Endoscopists have used spraying dye on the lining of bowel (Chromoendoscopy) successfully to improve detection of abnormal areas; however this is time consuming and requires extra time and equipment and despite the benefits seen in two studies is not widely used in routine clinical practice in the UK.

Narrow Band Imaging (NBI) is a technique that relies on light to improve contrast for the smallest blood vessels in the bowel lining which shows up precancerous areas as they have a richer vascular network. It is sometimes described as "digital chromoendoscopy" as the images produced are similar to chromoendoscopy, but it is much simpler and quicker to use. With magnification it allows assessment of the fine mucosal surace pattern (pit pattern) of lesion which allows an assessment of their likelihood of being precancerous. Autofluorescence endoscopy uses short wavelength light and light filters to produce a false colour image of the bowel lining where polyps stand out. These techniques have been used with some success in the oesophagus and stomach but little work is available for the colon.

We aim to see if NBI with magnification is better than standard colonoscopy for detecting precancerous areas. This is likely as it produces images similar to chromoendoscopy which is already shown to help. If a potentially precancerous area is found we will use other types of endoscopy, in particular NBI and autofluorescence to see if these techniques are helpful for discriminating between pre-cancerous and non-cancerous areas.

Magnification Narrow Band Imaging Colonoscopy for Hereditary Non-Polyposis Colorectal Cancer Surveillance

Back-to Back Trial of Narrow Band Imaging (NBI) With Magnification Versus Standard Colonoscopy for Colonic Neoplasia Surveillance in Hereditary Non-Polyposis Colorectal Cancer (HNPCC) Patients

London North West Healthcare NHS Trust

Carcinoma

Adenoma

Colonic Polyps

Polyps

After the caecum is reached patients will be first examined with high definition i-scan endoscopy. Each colonic segment will be investigated in a back to back fashion, during the second pass white light will be used.

After the caecum is reached patients will be first examined with high definition white light endoscopy. Each colonic segment will be investigated in a back to back fashion, during the second pass i-scan will be used.

Prior the colonoscopy patients will be randomized to white light first or i-scan first. After the caecum is reached patients will be first examined according to the randomization. Each colonic segment will be investigated in a back to back fashion, during the second pass the other modality will be used.

The use of I-scan in the detection of polyps in HNPCC

Raf Bisschops, MD PhD

Hereditary non-polyposis colon carcinoma (HNPCC or Lynch-Syndrome) is a rare cause of colorectal cancer caused by a gene defect in the so -called mismatch repair genes. Patients can present at young age with colorectal cancer and polyps can develop faster to malignant lesions in comparison to classical sporadic adenomas. New advanced imaging modalities with high definition images and virtual chromoendoscopy have a theoretical advantage to improve detection and to increase polyp detection. In patients with HNPCC polyp detection has been shown to be increased by classical chromo-endoscopy and by high definition endoscopy with narrow band imaging (NBI) (a virtual chromo-endoscopy modality activated by a button on the endoscope), in comparison to white light endoscopy. However, in these back-to-back studies there was no randomization for the order of imaging modality. It is therefore not clear whether really the image enhancement adds to increased polyp detection or if this is achieved by a second inspection of the mucosa. In this trial the investigators want to assess the real additional value of virtual chromo-endoscopy for polyp detection in patients with the Lynch syndrome. The investigators will use the high definition pentax system and will compare white light endoscopy to i-scan, the incorporated virtual chromo-endoscopy mode in this system.

Hereditary non-polyposis colon carcinoma (HNPCC) or the Lynch syndrome is a rare cause of colorectal cancer caused by a defect in mismatch repair genes. Because of this, colorectal cancer does not develop according to the classical adenoma-carcinoma sequence, resulting in faster progression to malignant lesions. As a results patients typically present at a younger age with colorectal cancer or associated cancers such as endometrium or ovarian cancer. The risk for cancer in patients with the Lynch syndrome has been estimated to be 60-90% for colon cancer presenting at a mean age of 44 years . Colonoscopy is considered the gold standard for polyp detection. However the polyp miss rate has been reported to be 2% for larger adenomas (\< 10mm) , 13% for lesions between 5 and 10 mm and up to 26% for small lesions (1-5 mm). Between 2 to 6 percent of carcinomas can be missed , resulting interval cancers. Typically, in HNPCC small colorectal lesions can already harbor cancer or high grade dysplasia, making early detection of small lesions even more clinically relevant than in an average risk population.

New endoscopic imaging systems that are currently available have a high definition video signal and have an incorporated feature of virtual chromoendoscopy. High definition endoscopy is becoming the new gold standard in endoscopy, since it is available in all new types of commercially available endoscopes. The use of high definition endoscopy may lead to improved recognition of subtle and flat lesions. Furthermore, the use of filters techniques accentuates superficial changes in the mucosal architecture and helps to characterize polyps. I-scan is a postprocessing filter incorporated in the high definition processor (EPKi) of the new Pentax endoscopes. The techniques highlights changes in surface and vessel architecture through 3 different modifications (so called surface enhancement, tone enhancement and contrast enhancement). In a randomized trial in patients with a positive feces occult blood test it has been shown that the system detects significantly more polyps than standard resolution white light.

Current literature suggests that classical chromoendoscopy with indigocarmine (Huneberg, lecomte) or narrow-band imaging (NBI) increases the detection of polyps in HNPCC patients. Although all of these studies had a cross-over design, randomization for the imaging modality was either not possible (in case of chromoendoscopy) or not applied (in case of NBI). So it is not clear whether more polyps are detected by advanced imaging techniques, or simply by a second inspection of the colon.

The aim of this study was to assess the additional value of i-scan in polyp detection in HNPCC patients in comparison to high definition white light endoscopy (HD-WLE) in a randomized controlled cross-over trial. The investigators also wanted to investigate the effect of a second inspection round on polyp detection.

I-Scan For Colon Polyp Detection In HNPCC

High Definition Endoscopy Versus Virtual Chromoendoscopy In The Detection Of Colonic Polyps In HNPCC

Universitaire Ziekenhuizen KU Leuven

Study title	NCT ID	Conditions	Interventions	Eligibility	Organization
Magnification Narrow Band Imaging Colonoscopy for Hereditary Non-Polyposis Colorectal Cancer Surveillance	NCT00313755	Colorectal Neop...	Narrow Band Ima...	18 Years -	London North West Healthcare NHS Trust
Magnification Narrow Band Imaging Colonoscopy for Hereditary Non-Polyposis Colorectal Cancer Surveillance	NCT00313755	Colorectal Neop...	Narrow Band Ima...	18 Years -	London North West Healthcare NHS Trust
I-Scan For Colon Polyp Detection In HNPCC	NCT01823471	Hereditary Non-... HNPCC Lynch Syndrome	The use of I-sc...	18 Years -	Universitaire Ziekenhuizen KU Leuven

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