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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.

Our results demonstrated that S-O clip-assisted ESD is safe and fast for en bloc resection of large superficial colorectal tumors.

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Background For almost 30 years, transanal endoscopic microsurgery (TEM) has been the mainstay treatment for large rectal lesions. With the advent of endoscopic submucosal dissection (ESD), flexible endoscopy has aimed at en bloc R0 resection of superficial lesions of the digestive tract. This systematic review and meta-analysis compared the safety and effectiveness of ESD and fullthickness rectal wall excision by TEM in the treatment of large nonpedunculated rectal lesions preoperatively assessed as noninvasive. Methods A systematic review of the literature published between 1984 and 2010 was conducted (Registration no. CRD42012001882). Data were integrated with those from the original databases requested from the study authors when needed. Pooled estimates of the proportions of patients with en bloc R0 resection, complications, recurrence, and need for further treatment in the ESD and TEM series were compared using random-effects single-arm meta-analysis. Results This review included 11 ESD and 10 TEM series (2,077 patients). The en bloc resection rate was 87.8 % (95 % confidence interval [CI] 84.3-90.6) for the ESD patients versus 98.7 % (95 % CI 97.4-99.3 %) for the TEM patients (P < 0.001). The R0 resection rate was 74.6 % (95 % CI 70.4-78.4 %) for the ESD patients versus 88.5 % (95 % CI 85.9-90.6 %) for the TEM patients (P < 0.001). The postoperative complications rate was 8.0 % (95 %, CI 5.4-11.8 %) for the ESD patients versus 8.4 % (95 % CI 5.2-13.4 %) for the TEM patients (P = 0.874). The recurrence rate was 2.6 % (95 % CI 1.3-5.2 %) for the ESD patients versus 5.2 % (95 % CI 4.0-6.9 %) for the TEM patients (P < 0.001). Nevertheless, the rate for the overall need of further abdominal treatment, defined as any type of surgery performed through an abdominal access, including both complications and pathology indications, was 8.4 % (95 % CI 4.9-13.9 %) for the ESD patients versus 1.8 % (95 % CI 0.8-3.7 %) for the TEM patients (P < 0.001). ConclusionsThe ESD procedure appears to be a safe technique, but TEM achieves a higher R0 resection rate when performed in full-thickness fashion, significantly reducing the need for further abdominal treatment. Keywords Rectal adenoma Transanal endoscopic microsurgery Endoscopic submucosal dissection Systematic review Meta-analysis For nearly 30 years, transanal endoscopic microsurgery (TEM) has been the optimal mainstay treatment for large rectal lesions. Initially conceived for treating benign lesions, its indications were extended to early rectal cancer treatment when Hermanek and Gall [1] assessed criteria to determine lesions at "low risk" for recurrence. One increasingly recognized advantage of the technique versus standard transanal surgery is the high rate of en bloc resection with disease-free margins, which is strictly related to the risk of recurrence [2]. With the advent of endoscopic submucosal dissection (ESD) about 10 years ago, flexible endoscopy permitted a surgical-like technique for en bloc resection of superficial lesions of the digestive trac...

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

Sessile serrated adenoma/polyp (SSA/P) is considered as an early precursor in the serrated neoplasia pathway leading to colorectal cancer development. The conventional adenoma-carcinoma sequence is associated with activation of the WNT signaling pathway, although its role in serrated lesions is still controversial. To clarify differences in WNT signaling activation in association with MLH1 methylation or BRAF/KRAS mutations between serrated and conventional routes, we performed b-catenin immunostaining, methylation-specific PCR for MLH1 and WNT signaling associated genes such as AXIN2, APC, and MCC and secreted frizzled-related proteins (SFRPs), and direct sequencing of BRAF/KRAS in 27 SSA/Ps, 14 SSA/Ps with high-grade dysplasia and 9 SSA/Ps with submucosal carcinoma, as well as 19 conventional adenomas, 26 adenomas with high-grade dysplasia and 25 adenomas with submucosal carcinoma. Nuclear b-catenin labelings were significantly lower in the serrated series than in their adenoma counterparts, and a significant increment in those labelings was found from SSA/Ps to those with high-grade dysplasia or submucosal carcinoma. The frequency of MLH1 and SFRP4 methylation was significantly higher in SSA/P series, as compared with corresponding adenoma series. AXIN2 and MCC were more frequently methylated in SSA/Ps with high-grade dysplasia and those with submucosal carcinoma than in adenoma counterparts. Stepwise increment of AXIN2 and MCC methylation was identified from SSA/Ps through those with high-grade dysplasia to those with submucosal carcinoma. A significant correlation was seen between nuclear b-catenin expression and methylation of AXIN2 or MCC in the SSA/P series. BRAF mutation was more frequent, whereas KRAS mutation was less frequent in the SSA/P series as compared with the adenoma series. There was an inverse association of BRAF mutation with AXIN2 methylation in SSA/P series. In conclusion, WNT/b-catenin signal activation mediated by the methylation of SFRP4, MCC, and AXIN2 may make different contributions to colorectal neoplasia between the serrated and conventional routes.