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      Narrow band imaging optical diagnosis of small colorectal polyps in routine clinical practice: the Detect Inspect Characterise Resect and Discard 2 (DISCARD 2) study

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          Abstract

          Background

          Accurate optical characterisation and removal of small adenomas (<10 mm) at colonoscopy would allow hyperplastic polyps to be left in situ and surveillance intervals to be determined without the need for histopathology. Although accurate in specialist practice the performance of narrow band imaging (NBI), colonoscopy in routine clinical practice is poorly understood.

          Methods

          NBI-assisted optical diagnosis was compared with reference standard histopathological findings in a prospective, blinded study, which recruited adults undergoing routine colonoscopy in six general hospitals in the UK. Participating colonoscopists (N=28) were trained using the NBI International Colorectal Endoscopic (NICE) classification (relating to colour, vessel structure and surface pattern). By comparing the optical and histological findings in patients with only small polyps, test sensitivity was determined at the patient level using two thresholds: presence of adenoma and need for surveillance. Accuracy of identifying adenomatous polyps <10 mm was compared at the polyp level using hierarchical models, allowing determinants of accuracy to be explored.

          Findings

          Of 1688 patients recruited, 722 (42.8%) had polyps <10 mm with 567 (78.5%) having only polyps <10 mm. Test sensitivity (presence of adenoma, N=499 patients) by NBI optical diagnosis was 83.4% (95% CI 79.6% to 86.9%), significantly less than the 95% sensitivity (p<0.001) this study was powered to detect. Test sensitivity (need for surveillance) was 73.0% (95% CI 66.5% to 79.9%). Analysed at the polyp level, test sensitivity (presence of adenoma, N=1620 polyps) was 76.1% (95% CI 72.8% to 79.1%). In fully adjusted analyses, test sensitivity was 99.4% (95% CI 98.2% to 99.8%) if two or more NICE adenoma characteristics were identified. Neither colonoscopist expertise, confidence in diagnosis nor use of high definition colonoscopy independently improved test accuracy.

          Interpretation

          This large multicentre study demonstrates that NBI optical diagnosis cannot currently be recommended for application in routine clinical practice. Further work is required to evaluate whether variation in test accuracy is related to polyp characteristics or colonoscopist training.

          Trial registration number

          The study was registered with clinicaltrials.gov (NCT01603927).

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          Most cited references 35

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          Genetic alterations during colorectal-tumor development.

          Because most colorectal carcinomas appear to arise from adenomas, studies of different stages of colorectal neoplasia may shed light on the genetic alterations involved in tumor progression. We looked for four genetic alterations (ras-gene mutations and allelic deletions of chromosomes 5, 17, and 18) in 172 colorectal-tumor specimens representing various stages of neoplastic development. The specimens consisted of 40 predominantly early-stage adenomas from 7 patients with familial adenomatous polyposis, 40 adenomas (19 without associated foci of carcinoma and 21 with such foci) from 33 patients without familial polyposis, and 92 carcinomas resected from 89 patients. We found that ras-gene mutations occurred in 58 percent of adenomas larger than 1 cm and in 47 percent of carcinomas. However, ras mutations were found in only 9 percent of adenomas under 1 cm in size. Sequences on chromosome 5 that are linked to the gene for familial adenomatous polyposis were not lost in adenomas from the patients with polyposis but were lost in 29 to 35 percent of adenomas and carcinomas, respectively, from other patients. A specific region of chromosome 18 was deleted frequently in carcinomas (73 percent) and in advanced adenomas (47 percent) but only occasionally in earlier-stage adenomas (11 to 13 percent). Chromosome 17p sequences were usually lost only in carcinomas (75 percent). The four molecular alterations accumulated in a fashion that paralleled the clinical progression of tumors. These results are consistent with a model of colorectal tumorigenesis in which the steps required for the development of cancer often involve the mutational activation of an oncogene coupled with the loss of several genes that normally suppress tumorigenesis.
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            Annual report to the nation on the status of cancer, 1975-2006, featuring colorectal cancer trends and impact of interventions (risk factors, screening, and treatment) to reduce future rates.

            The American Cancer Society, the Centers for Disease Control and Prevention (CDC), the National Cancer Institute (NCI), and the North American Association of Central Cancer Registries (NAACCR) collaborate annually to provide updated information regarding cancer occurrence and trends in the United States. This year's report includes trends in colorectal cancer (CRC) incidence and death rates and highlights the use of microsimulation modeling as a tool for interpreting past trends and projecting future trends to assist in cancer control planning and policy decisions. Information regarding invasive cancers was obtained from the NCI, CDC, and NAACCR; and information on deaths was obtained from the CDC's National Center for Health Statistics. Annual percentage changes in the age-standardized incidence and death rates (based on the year 2000 US population standard) for all cancers combined and for the top 15 cancers were estimated by joinpoint analysis of long-term trends (1975-2006) and for short-term fixed-interval trends (1997-2006). All statistical tests were 2-sided. Both incidence and death rates from all cancers combined significantly declined (P < .05) in the most recent time period for men and women overall and for most racial and ethnic populations. These decreases were driven largely by declines in both incidence and death rates for the 3 most common cancers in men (ie, lung and prostate cancers and CRC) and for 2 of the 3 leading cancers in women (ie, breast cancer and CRC). The long-term trends for lung cancer mortality in women had smaller and smaller increases until 2003, when there was a change to a nonsignificant decline. Microsimulation modeling demonstrates that declines in CRC death rates are consistent with a relatively large contribution from screening and with a smaller but demonstrable impact of risk factor reductions and improved treatments. These declines are projected to continue if risk factor modification, screening, and treatment remain at current rates, but they could be accelerated further with favorable trends in risk factors and higher utilization of screening and optimal treatment. Although the decrease in overall cancer incidence and death rates is encouraging, rising incidence and mortality for some cancers are of concern. Copyright 2009 American Cancer Society.
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              The Paris endoscopic classification of superficial neoplastic lesions: esophagus, stomach, and colon: November 30 to December 1, 2002.

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                Author and article information

                Affiliations
                [1 ]Department of Gastroenterology, South Tyneside NHS Foundation Trust , South Shields, UK
                [2 ]School of Medicine, Pharmacy and Health, Durham University , Durham, UK
                [3 ]Northern Region Endoscopy Group, UK
                [4 ]St Mark's Hospital and Academic Institute, London North West Healthcare NHS Trust, Imperial College London , London, UK
                [5 ]Durham Clinical Trials Unit, School of Medicine Pharmacy & Health, Durham University , Stockton-on-Tees, UK
                [6 ]Department of Gastroenterology, North Tees & Hartlepool NHS Foundation Trust , Stockton-on-Tees, UK
                [7 ]Translational Gastroenterology Unit, John Radcliffe Hospital, University of Oxford , Oxford, UK
                [8 ]Department of Gastroenterology, Northumbria Healthcare NHS Foundation Trust , Newcastle upon Tyne, UK
                [9 ]Department of Gastroenterology, North Cumbria University Hospitals NHS Trust , Carlisle, UK
                [10 ]Department of Gastroenterology, South Tees Hospitals NHS Foundation Trust , Middlesborough, UK
                [11 ]Department of Gastroenterology, County Durham & Darlington NHS Foundation Trust , Darlington, UK
                [12 ]Warwick Medical School, University of Warwick , Coventry, UK
                Author notes
                [Correspondence to ] Professor Colin J Rees, Department of Gastroenterology, South Tyneside District Hospital, South Shields NE34 0PL, UK; Colin.Rees@ 123456stft.nhs.uk
                Journal
                Gut
                Gut
                gutjnl
                gut
                Gut
                BMJ Publishing Group (BMA House, Tavistock Square, London, WC1H 9JR )
                0017-5749
                1468-3288
                May 2017
                19 April 2016
                : 66
                : 5
                : 887-895
                gutjnl-2015-310584
                10.1136/gutjnl-2015-310584
                5531217
                27196576
                (Collab), (Collab), (Collab), (Collab), (Collab), (Collab), (Collab), (Collab), (Collab), (Collab), (Collab), (Collab), (Collab), (Collab), (Collab), (Collab), (Collab), (Collab), (Collab), (Collab), (Collab), (Collab), (Collab), (Collab), (Collab), (Collab), (Collab), (Collab), (Collab), (Collab), (Collab)
                Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

                This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/

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                1506
                Endoscopy
                Original article
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                Gastroenterology & Hepatology

                colonic neoplasms, colorectal adenomas, colonoscopy, endoscopy

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