Digestive EndoscopyHigh definition plus colonoscopy combined with i-scan tone enhancement vs. high definition colonoscopy for colorectal neoplasia: A randomized trial
Introduction
Colorectal cancer (CRC) is one of the most common malignant tumours in the world; advanced tumours still have a disappointing 5-year survival rate [1], [2]. Timely detection and removal of all premalignant lesions help to prevent the disease. Colonoscopy is the gold standard for CRC screening because it permits detection and removal of pre-cancerous polyps during the examination [3], [4], [5].
However, not all adenomatous polyps are identified during screening and surveillance colonoscopy; some patients develop colorectal cancer even under colonoscopic surveillance [6]. This may be caused by the rapid progression of adenomas or overlooked colorectal lesions. A meta-analysis of 6 studies by Van Rijn et al., in which patients went through two colonoscopies the same day, reported a polyp miss rate of 22% [5].
Efforts to improve endoscopic detection of adenomatous polyps include changes in procedural aspects (increased withdrawal time, looking behind colonic folds) and the use of advanced optical technologies. The aims were to reduce miss rates of adenomas and optimize prevention of colorectal cancer.
A well established technology today is high-definition white light (HDWL) endoscopy, which can be used with or without optical filters to selectively illuminate tissue. Of the new endoscopic imaging techniques, i-scan is a digital contrast method with three modes of image enhancement [7]. I-scan 1 enhances light-dark contrast by obtaining luminance intensity data for each pixel and applying an algorithm that allows detailed observation of the structure of the mucosal surface, whereas i-scan 2/3 dissects and analyzes the individual RGB components of a normal image and recombines the components into a single, new colour image. This mode has been designed to increase mucosal and vascular contrast between suspicious and normal tissue, as in vivo chromoendoscopy does. The exact i-scan settings are recommended by the manufacturer's protocol.
Adenoma detection rates with various white light endoscopy methods have been compared in several studies, but just a few studies have addressed the usefulness of optical filters during withdrawal in a back-to-back manner. The majority of studies report controversial results concerning the usefulness of filters for the detection of colonic lesions. We conducted, for the first time, a randomized controlled trial with the primary aim of prospectively determining whether the use of i-scan 2 colonoscopy is associated with a higher adenoma detection rate in average-risk individuals undergoing colon cancer screening and surveillance compared with the widely used procedure of high-definition white light colonoscopy.
Section snippets
Patients and methods
A single-centre trial was performed at the interdisciplinary endoscopic unit at Johannes Gutenberg University of Mainz. Patients were selected from those scheduled to undergo routine screening or surveillance colonoscopy at the division of gastroenterology and hepatology, University Hospital of Mainz, who provided informed consent.
Patients were eligible for the study (inclusion criteria) when they had an indication for colon cancer screening, post-polypectomy surveillance, or a positive occult
Results
One hundred patients were deemed eligible for the study; 20 patients were excluded because of failure of cecal intubation (n = 5), poor or inadequate bowel preparation (n = 12), or suspected inflammatory bowel disease (n = 3). Thus, 80 patients were included, of whom 40 were randomly assigned to the control group and 40 to the study group (Fig. 3). No other procedural complications occurred. All endoscopists performed both types of colonoscopies. No significant differences existed among the studied
Discussion
Colorectal cancer (CRC) is the second leading cause of cancer in the Western world [13], [14], [15]. More than 90% of CRC incidents develop over several years from polyps that grow in the colon [15], [16], [17], [18]. Effective detection and subsequent removal of the polyps prevent the disease. Although colonoscopy with adenoma removal can prevent colorectal cancer in as many as 76–90% of cases, we know that some patients undergoing colonoscopy with adenoma removal still develop colorectal
Conflict of interest
None declared.
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