title: The efficacy of endoscopic submucosal dissection for colorectal tumors extending to the dentate line.
abstract: OBJECTIVE
  Although endoscopic submucosal dissection (ESD) is becoming the mainstay of the treatment strategies, rather than surgical treatment, for colorectal tumors extending to the dentate line, ESD is technically more difficult. This study was aimed at assessing the usefulness of ESD for the treatment of colorectal tumors extending to the dentate line.
  
  
  METHODS
  This study included 531 patients with colorectal tumors who underwent colorectal ESD between 2008 and 2015. They were divided into three groups: rectal tumors extending to the dentate line (anorectal group), those not extending to the dentate line (proximal rectal group), and colonic tumors (colonic group), and a retrospective comparative analysis was carried out.
  
  
  RESULTS
  Of the total patients, 18 (3.4%) had lesions extending to the dentate line area. The procedure times were 103.4 ± 84.0, 80.4 ± 64.3, and 71.8 ± 52.3 min, respectively (P = 0.0318). All the patients in the anorectal group were operated by operators who had performed at least 20 colorectal ESDs (P < 0.0001). No significant difference among the three groups was found in the en bloc resection rate, complete resection rate, or curative resection rate. Although no significant difference in the incidence of perforation was observed among the three groups, intraoperative bleeding was observed in 61% of the patients in the anorectal group (P < 0.0001).
  
  
  CONCLUSIONS
  ESD is an effective treatment strategy for colorectal tumors extending to the dentate line. However, it seems that anorectal ESD, which is technically more difficult than colorectal ESD, should be performed by operators with ample experience in performing ESD.
authors.affiliation: Department of Gastroenterology, Saitama Medical Center, Jichi Medical University, 1-847 Amanuma, Omiya, Saitama, 330-8503, Japan. s.w.himananon@ac.auone-net.jp.
authors.forename: Satohiro
authors.initials: S
authors.lastname: Matsumoto
authors.affiliation: Department of Gastroenterology, Saitama Medical Center, Jichi Medical University, 1-847 Amanuma, Omiya, Saitama, 330-8503, Japan.
authors.forename: Hirosato
authors.initials: H
authors.lastname: Mashima
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003110:Colonic Neoplasms / Q000601:surgery; D015179:Colorectal Neoplasms / Q000473:pathology / Q000601:surgery*; D000069916:Endoscopic Mucosal Resection; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012004:Rectal Neoplasms / Q000601:surgery; D016896:Treatment Outcome
keywords: Anorectal neoplasms; Colorectal neoplasms; Dentate line; Endoscopic submucosal dissection