Many clinical studies on narrow-band imaging (NBI) magnifying endoscopy classifications advocated so far in Japan (Sano, Hiroshima, Showa, and Jikei classifications) have reported the usefulness of NBI magnifying endoscopy for qualitative and quantitative diagnosis of colorectal lesions. However, discussions at professional meetings have raised issues such as: (i) the presence of multiple terms for the same or similar findings; (ii) the necessity of including surface patterns in magnifying endoscopic classifications; and (iii) differences in the NBI findings in elevated and superficial lesions. To resolve these problems, the Japan NBI Expert Team (JNET) was constituted with the aim of establishing a universal NBI magnifying endoscopic classification for colorectal tumors (JNET classification) in 2011. Consensus was reached on this classification using the modified Delphi method, and this classification was proposed in June 2014. The JNET classification consists of four categories of vessel and surface pattern (i.e. Types 1, 2A, 2B, and 3). Types 1, 2A, 2B, and 3 are correlated with the histopathological findings of hyperplastic polyp/sessile serrated polyp (SSP), low-grade intramucosal neoplasia, high-grade intramucosal neoplasia/shallow submucosal invasive cancer, and deep submucosal invasive cancer, respectively.

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The Colonoscopy Screening and Surveillance Guidelines were developed by the Japan Gastroenterological Endoscopy Society as basic guidelines based on the scientific methods. The importance of endoscopic screening and surveillance for both detection and post-treatment follow-up of colorectal cancer has been recognized as essential to reduce disease mortality. There is limited high-level evidence in this field; therefore, we had to focus on the consensus of experts. These clinical practice guidelines consist of 20 clinical questions and eight background knowledge topics that have been determined as the current guiding principles.

Based on the present data, we reached a consensus for developing the JNET classification.

This diagnostic tool may lead to the reduction of unnecessary treatments for non-neoplastic lesions.

In comparison with protruding adenomas, depressed adenomas were rare and appeared endoscopically as large and reddish with a specific regular ultrafine network pattern of mucosal microvasculature. Depressed adenomas should be endoscopically resected because intramucosal carcinomas were found in a quarter of them.

IntroductionEarly detection and removal of colorectal neoplasia are essential in reducing mortality rates for patients with colorectal cancer [1,2]. Although several modalities are available for colorectal cancer screening [3 -6], colonoscopy is considered the most effective because it allows direct visualization and onsite treatment of encountered lesions. Accurately determining the histological features of colorectal polyps using endoscopy could prevent unnecessary endoscopic treatments thus allowing the proposal of adequate surveillance recommendations [7]. Magnifying narrow-band imaging (NBI) enables detailed observation of the microvascular architecture of lesions and can be used for endoscopic differential diagnosis and estimaEffectiveness of computer-aided diagnosis of colorectal lesions using novel software for magnifying narrow-band imaging: a pilot study

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