Endoscopic Resection Technique Used for Complete En Bloc Resection of T1b Colorectal Cancer Takashi Toyonaga 1 , Hiroya Sakaguchi 2 , Nobuaki Ikezawa 2 , Yoshiko Nakano 2 , Shinwa Tanaka 2 , Tsukasa Ishida 2 , Hirofumi Abe 2 , Tetsuya Yoshizaki 2 , Toshitatsu Takao 2 , Yoshinori Morita 2 , Shinichi Baba 3 , Hiroshi Takihara 3 , Eisei Nishino 4 , Hiroshi Yokozaki 5 , Yuzo Kodama 2 1Department of Endoscopy, Kobe University Hospital, Kobe, Japan 2Department of Gastroenterology, Kobe University Graduate School of Medicine, Kobe, Japan 3Department of Gastroenterology, Kishiwada Tokushukai Hospital, Kishiwada, Japan 4Department of Pathology, Kishiwada Tokushukai Hospital, Kishiwada, Japan 5Division of Pathology, Department of Pathology, Kobe University Graduate School of Medicine, Kobe, Japan Keyword: 大腸T1b癌 , MR sign , ESD , PCM , PAEM pp.1047-1056
Published Date 2021/7/25
DOI https://doi.org/10.11477/mf.1403202505
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 The frequency of ESD(performing endoscopic submucosal dissection)in the treatment of cT1b colorectal cancer, including its use in diagnostic resection, has increased because of the advancement of ESD, aging of population, and the presence of comorbidities. This trend is particularly apparent in cases with rectal cancer, in which accurate assessment of the depth of invasion, presence/absence of lymphatic/blood vessel invasion, histological classification, and budding grade is required to determine the need for additional surgery. However, T1b cancer lesions can be associated with severe fibrotic changes and MR(muscle retracting)signs in the submucosal layer, which not only make ESD technically difficult but also are important metastatic risk factors that are likely to be damaged during dissection. Based on the introduction of PCM(the pocket creation method)and the experience with POEM(per-oral endoscopic myotomy)/POET(per-oral endoscopic tumor resection)in the esophagus, we devised PAEM(per-anal endoscopic myectomy), for rectal lesions with severe fibrosis, in which dissection is performed between the inner circular and outer longitudinal muscles. The resected specimens that include the entire submucosal layer can be obtained by resecting the inner circular muscles together. Although PAEM is an reliable endoscopic resection technique for complete en bloc resection of T1b cancer in the lower rectum, future use in the accurate diagnosis of T2 cancer should be established.

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