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Colorectal cancer is a heterogeneous oncological disease that develops through several molecular pathways. Each pathway is associated with specific neoplastic precursor lesions. Classification of colorectal polyps and the molecular features of associated colorectal cancers have undergone significant changes. An understanding of colorectal carcinogenesis and the molecular features of colorectal carcinomas is now regarded as necessary for personalized treatment and management of patients with colon cancer, and even for patients undergoing screening colonoscopy for early detection and prevention of colorectal cancer. In the present review, we describe the pathological and molecular features of epithelial precursor lesions involved in the early phases of colorectal carcinogenesis.

Colonoscopy is considered the best modality for the detection and treatment of colorectal polyps. However, some polyps still may not be detected. Although conventional white-light endoscopy is the gold standard for the detection of colorectal polyps, up to a fifth of lesions may be missed on screening colonoscopy, especially non-polypoid colorectal neoplasms. Recently, many studies have reported on various endoscopic modalities that improve the detection and characterization of colorectal lesions. Newly developed modalities might be helpful to recognize colorectal lesions; however, careful observation is required to identify flat/depressed lesions as well as hidden polyps during screening and surveillance colonoscopy.

Background and AimThe existence of other primary tumors during the treatment and management of gastric cancer (GC) is an important issue. The present study investigated the prevalence and management of synchronous colorectal neoplasms (CRN) in surgically treated GC patients. MethodsOf 381 surgically treated GC patients, 332 (87.1%) underwent colonoscopy to detect CRN before surgery or within a year after surgery. ResultsCRN were synchronously observed in 140 patients (42.2%). Adenoma was observed in 131 patients (39.4%). Endoscopic resection was done in 18 patients with adenoma. Colorectal cancer (CRC) was observed in 16 patients (4.8%), superficial CRC in 13 and advanced CRC in three patients. Endoscopicresection of superficial CRC was carried out in seven patients, whereas simultaneous surgical resection of CRC was done in nine patients. CRN were more frequently observed in men. CRC was more frequently observed in GC patients with distant metastasis, albeit without significance. The overall survival of GC patients with CRN or CRC was poorer than that of patients without CRN or CRC. ConclusionSynchronous CRN were commonly associated with GC and screening colonoscopy should be offered to patients with GC., Article, DIGESTIVE ENDOSCOPY. 26(3):396-402 (2014)

During colonoscopy, small and diminutive colorectal polyps are commonly encountered. It is estimated that at least one adenomatous polyp is detected in almost half of all patients undergoing screening colonoscopy. In contrast, the ‘predict, resect, and discard’ strategy for diminutive and small colorectal polyps is a current topic especially in Western countries. ‘Is this an acceptable policy in Japan?’ Herein, we report the results of a questionnaire survey with regard to the management of diminutive colorectal polyps, including the thoughts of Japanese endoscopists regarding the ‘predict, resect, and discard’ strategy. At the moment, we propose that this strategy should be used by skilled endoscopists only.

Background and Aim A ‘resect and discard’ strategy using non-magnifying narrow band imaging (N-NBI) has been proposed for reducing screening colonoscopy costs, but it does not take into consideration advanced histology and magnifying NBI (M-NBI) that can potentially further improve the ‘resect and discard’ strategy. We conducted a pilot study to investigate the feasibility of M-NBI for the new ‘resect and discard’ strategy with consideration for advanced histology. Methods The present study involved 63 patients. For each polyp, optical diagnosis was independently made using N-NBI and M-NBI, a decision (discard or send for pathology) was made based on the M-NBI findings, and histological and optical diagnosis results were compared. Results Sensitivity, specificity and accuracy (95% confidence interval) of M-NBI for lesions with advanced histology were 1.00 (0.36–1.00), 0.92 (0.91–0.92) and 0.92 (0.90–0.92), respectively. Whereas the management of 86% of small polyps could be decided without formal histopathology, lesions with advanced histology were not discarded using M-NBI. The diagnostic accuracy of M-NBI in distinguishing neoplastic from non-neoplastic lesions was higher than that of N-NBI. Conclusions We propose a new resect and discard strategy with advanced histology using M-NBI that is a promising strategy to reduce the costs of histopathology and to minimize the risk of discarding important lesions.

Flat and depressed (nonpolypoid) colorectal lesions have been described for over two decades by Japanese investigators. These neoplastic lesions are typically smaller than polypoid ones and can be more difficult to identify during screening colonoscopy. In particular, depressed type colorectal lesions are usually small in size, with a number of studies showing them to be at greater risk for developing high-grade dysplasia or submucosal invasive cancer. It has also been suggested that they may follow a different carcinogenic pathway to flat elevated or protruding adenomas. This paper summarizes recent data of nonpolypoid colorectal neoplasms from Western and Asian countries.

Narrow band-imaging (NBI) enhances mucosal visualization of the vascular network and surface structure and helps to increase the visibility of neoplasia by improving contrast. Studies on the detectability of colorectal neoplastic lesions using NBI have primarily been reported in Western countries, but the published opinions and conclusions remain controversial at the present time. Our earlier prospective pilot study demonstrated that NBI colonoscopy significantly improved detection of flat lesions, which are more likely to be missed, particularly on the right side of the colon. It is especially important that even examiners performing routine screening colonoscopies become sufficiently familiar with flat and depressed lesions and then take full advantage of the endoscopic systems and specific image enhancement functions currently available for improved detection of flat and diminutive lesions. Adequate bowel preparation is another important consideration.