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Contains fulltext : 205162.pdf (Publisher’s version ) (Open Access) BACKGROUND AND AIMS: Colorectal cancer (CRC) is largely preventable with routine screening and surveillance colonoscopy; however, interval cancers arising from precancerous lesions missed by standard colonoscopy still occur. An increased adenoma detection rate (ADR) has been found to be inversely associated with interval cancers. The G-EYE device includes a reusable balloon integrated at the distal tip of a standard colonoscope, which flattens haustral folds, centralizes the colonoscope's optics, and reduces bowel slippage. The insufflated balloon also aims to enhance visualization of the colon during withdrawal, thereby increasing the ADR. METHODS: In this randomized, controlled, international, multicenter study (11 centers), patients (aged >/=50 years) referred to colonoscopy for screening, surveillance, or changes in bowel habits were randomized to undergo either balloon-assisted colonoscopy by using an insufflated balloon during withdrawal or standard high-definition colonoscopy. The primary endpoint was the ADR. RESULTS: One thousand patients were enrolled between May 2014 and September 2016 to undergo colonoscopy by experienced endoscopists; 803 were finally analyzed (standard colonoscopy n = 396; balloon-assisted colonoscopy n = 407). Baseline parameters were similar in both groups. Balloon-assisted colonoscopy provided a 48.0% ADR compared with 37.5% in the standard colonoscopy group (28% increase; P = .0027). Additionally, balloon-assisted colonoscopy provided for a significant increase in detection of advanced (P = .0033) flat adenomas (P < .0001) and sessile serrated adenomas/polyps (P = .0026). CONCLUSION: Balloon-assisted colonoscopy yielded a higher ADR and increased the detection of advanced, flat, and sessile serrated adenomas/polyps when compared with standard colonoscopy. Improved detection by the G-EYE device could impact the quality of CRC screening by reducing miss rates and consequently reducing interval cancer incidence. (Clinical trial registration number: NCT01917513.).

Su1702 Diagnostic Characteristics of Depressed Type Colorectal Neoplasms Examined With Magnifying Chromo-Endoscopy and Endocytoscopy Shin-Ei Kudo*, Kazuki Kato, Katsuro Ichimasa, Hideyuki Miyachi, Yuta Kouyama, Shingo Matsudaira, Hiromasa Oikawa, Tomokazu Hisayuki, Yui J. Kimura, Yuichi Mori, Masashi Misawa, Toyoki Kudo, Kenta Kodama, Kunihiko Wakamura, Takemasa Hayashi, Atsushi Katagiri, Eiji Hidaka, Fumio Ishida Showa University Northern Yokohama Hospital, Yokohama, Japan Introduction & Aim: Colorectal carcinomas are generally recognized to develop from sessile-type “polyps”. This “adenoma-carcinoma sequence” theory has been in the mainstream of development of colorectal cancers. But recently the existence of many depressed-type cancers has been revealed, which are considered to emerge directly from normal epithelium, not through the adenomatous stage. This theory is called “de novo” pathway. Now, it is possible to estimate the histology of colorectal lesions using magnifying chromo-endoscopy (pit pattern classification) and endocytoscopy (EC) which can observe not only the structural atypia but also the cellular atypia in living colorectal lesions. The aim is to clarify the diagnostic characteristics of depressed-type colorectal neoplasms, demonstrating the validity of pit pattern diagnosis and EC classification. Methods: A total of 22903 colorectal neoplasms excluding advanced carcinomas were resected endoscopically or surgically in our unit from April 2001 to June 2014. Of these, 14522 lesions were low-grade dysplasia, 4956 were high-grade dysplasia and 968 were submucosally invasive (T1) carcinomas. According to morphological/development classification, they were divided into 3 types: depressed, flat and sessile type. We investigated the rate of T1 carcinomas and the characteristics of depressed-type neoplasms concerning pit pattern and EC classification. Results: The rate of T1 carcinomas in depressed-type lesions reached to 63.7 %, meanwhile that in flat-type and sessile-type lesions was 4.1 % and 3.1 %, respectively. Within less than 5mm in diameter, that was 10.2 %, 0 % and 0.06 %, respectively. Most (88.3 % and 91.2 %) of the flat-type and sessile-type lesions showed type IIIL or IV pit pattern corresponding to adenomas, whereas 94.5 % of the depressed-type lesions were characterized by type IIIs, VI or VN pit pattern corresponding to carcinomas. As for endocytoscopy, most of the flatand sessile-type lesions showed EC2 corresponding to adenomas. In contrast, the depressed-type lesions were observed as EC3a (23.5 %) and EC3b (74.1 %) corresponding to invasive carcinomas. Conclusion: This study revealed the diagnostic characteristics of depressed-type lesions. They show typically type IIIs, VI or VN pit patterns in magnifying endoscopy and type EC3a or EC3b in endocytoscopy. These lesions tend to invade the submucosal layer even when they are small. Therefore, more careful endoscopic diagnosis of ‘whether the lesion is depressed type or not’ would be important.