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NBI Versus White Light Endoscopy for Optical Characterization of Neoplastic Polyps in the Colorectum

ABSTRACT: Adenomas, serrated adenomas and hyperplastic polyps are polypoid lesion in the colorectum. At the present moment, all polyps should be resected endoscopically, although only adenomas and serrated adenomas, but not hyperplastic polyps have the potential to develop colorectal cancer. This approach enables the conduction of microscopic investigations of the lesions. By today, only the pathological diagnosis can distinguish exactly between these three polyp entities. Some studies have investigated the value of the optical characterization approach which is based on visual assessment of the polyp’ surface structures. Based upon optical polyp features users are encouraged to predict histopathological polyp diagnoses solely on behalf of optical or endoscopical criteria. This method is conducted in real time during colonoscopy. If it could be shown, that endoscopist using the optical characterization approach are able to predict histopathological diagnoses of colonic polyps sufficiently this would possibly lead to simplification of diagnostic procedures. For instance, it would be conceivable to resect small polyps and discard them without further assessment by a pathologist. One problem in this context is a correct differentiation between hyperplastic polyps and serrated adenomas. These two polyp entities are known to show similar optical features. However, while serrated adenomas are premalignant lesions hyperplastic polyps have benign histology and never develop into cancer. It is therefore important to sufficiently distinguish hyperplastic polyps from serrated lesions. In this study we want to investigate whether the use of narrow-band imaging (NBI) would be capable to rise accuracy of optical polyp predictions compared to standard HD white light endoscopy. NBI is a light filter tool which can be activated by pressing a button at the endoscope. The use of NBI leads to an endoscopic picture which appears blue and enables endoscopists to better assess surface structures and vascular patterns. In a prospective randomised multicenter setting we plan to conduct colonoscopy in 370 patients. Half of the patients will be examined without the use of NBI (control arm). In these cases colonoscopists will assess optical diagnosis of polyps without turning on the NBI tool. If polyps are detected in patients belonging to the intervention arm NBI will be used and optical diagnosis will be determined using the WASP (Workgroup serrAted polypS and Polyposis) classification. All polyps will be resected and send to pathology for further microscopic assessment. After completing the trial we aim to compare accuracy of the optical diagnosis in both groups. Our hypothesis is, that by using NBI accordance between optical and histopathological diagnosis can be increased from 80% to 90%.

DISEASE(S): Colorectal Carcinoma,Hyperplastic Polyp,Colon Adenoma,Colorectal Neoplasms,Adenoma,Serrated Adenoma,Polyps

PROVIDER: 2284776 | ecrin-mdr-crc |

REPOSITORIES: ECRIN MDR

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Project description:Sessile serrated adenomas are now recognized as precursor lesions of a substantial subset of colorectal cancers arising via a so-called “serrated pathway”. However, their biological markers remain to be defined. The aim of our study was to identify differentially expressed genes in sessile serrated adenomas, hyperplastic polyps and tubular adenomas. Gene expression analysis demonstrated molecular differences between polyp types. Further studies using QRT-PCR on Cathepsin E demonstrated a significantly (p< 0.05) higher expression in sessile serrated adenomas as compared to both other polyp types. Trefoil Factor 1, showed the same trend of expression for sessile serrated adenomas as compared to hyperplastic polyps, and was significantly higher in both polyps compared to tubular adenomas. Immunohistochemistry for both proteins demonstrated strong cytoplasmic staining of abnormal crypts in all sessile serrated adenomas while staining in tubular adenomas and hyperplastic polyps was weak and focal. BRAF and KRAS mutation analysis were employed to further validate polyp discrimination. The findings demonstrated the positive association of the BRAF mutation, V600E, with sessile serrated adenomas and KRAS mutations with tubular adenomas (P<0.05). This study demonstrates CTSE and TFF1 over-expression in sessile serrated adenomas compared to both hyperplastic polyps and tubular adenomas. Keywords: colonic polyp tissue comparison, linear modelling, SSA Microarray analysis was performed on 13 SSAs and 11 TAs. SSAs were from 4 males and 9 females (mean age of 75) and TAs were from 5 males and 6 females (mean age of 72). Samples were directly hybridised to each other (SSA versus TA) or to a pooled normal control (SSA versus control). A linear model (Smyth 2004) was fitted to the data bringing together the three contrasts: SSA versus control, TA versus control and SSA versus TA. Human OligoLibrary (Compugen Human Oligo Library (v1) containing 18861 60-mer oligonucleotides, representing approximately 16,000 unique genes) by the Adelaide Microarray Centre (Australia) was used. Slides were scanned using a GenePix 3000B scanner (Axon Instruments, Sunnydale, CA), and the Spot package (CSIRO, Australia) was used to identify spots and estimate fore- and background intensities (using a morphological opening background estimator) (Yang, Buckley et al. 2001; Ritchie 2004). Data analysis was performed in R (www.r-project.org) using the Limma package of Bioconductor (Gentleman, Carey et al. 2004; Smyth 2004). Loess print tip method was used to correct for dye-bias and intensity within each group of adjacent spots printed by one pin (Yang, Dudoit et al. 2002). Linear modelling was performed with the Limma package of Bioconductor (Smyth 2004).

Project description:Adenomas and hyperplastic polyps are polypoid lesion and may occur at any location in the colon. At the present moment, all polyps should be resected endoscopically, although only adenomas, but not hyperplastic polyps have the potential to develop colorectal cancer. This approach enables the conduction of microscopic investigations of the lesions. By today, only the pathological diagnosis can distinguish exactly between adenomas and hyperplastic polyps. Some studies have investigated the value of the socalled optical biopsy method. Optical biopsy means the visual assessment of the polyp and the determination of a diagnosis solely on behalf of optical criteria. This method is conducted in real time during colonoscopy. If it can be shown, that endoscopist using optical biopsy are able to predict histopathological diagnoses of colonic polyps sufficiently this would possibly lead to simplification of diagnostic procedures. For instance, it would be conceivable to resect hyperplastic polyps and small adenomas and discard them without further assessment by a pathologist. Gastroenterological societies demand for a 90 percent accordance between diagnoses set by endoscopists and pathologists as a prerequisite for the implementation of the optical biopsy method. In this study we want to proof that the use of a new narrow-band imaging (NBI) tool (Exera III, Olmpus) is capable to rise accuracy of optically ascertained diagnoses of colonic polyps. NBI is a light filter tool which can be activated by pressing a button at the endoscope. NBI function leads to an endoscopic picture which appears blue and enables endoscopists to better assess surface structures and vascular patterns. In a prospective randomised multicenter setting we plan to conduct colonoscopy in 380 patients. Half of the patients will be examined without use of NBI (control arm). In these cases colonoscopists will assess optical diagnosis of polyps without turning on the NBI tool. If polyps are detected in patients belonging to the intervention arm NBI will be used and optical diagnosis will be determined using the NICE (NBI International Colorectal Endoscopic) classification. All polyps will be resected and send to pathology for further microscopic assessment. After completing the trial we aim to compare accuracy of the optical diagnosis in both groups. Our hypothesis is, that by using the new NBI tool accuracy (accordance between optical and histopathological diagnosis) can be increased from 78% to 90%.

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NBI Versus White Light Endoscopy for Optical Characterization of Neoplastic Polyps in the Colorectum

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