title: Retrospective study of technical aspects and complications of endoscopic submucosal dissection for large superficial colorectal tumors.
abstract: OBJECTIVE
  Colorectal endoscopic submucosal dissection (ESD) is widely carried out, but is still considered difficult. In 2010, a tumor size of ≥ 50 mm and less experience in colorectal ESD were reported as independent risk factors for complications such as perforation, delayed perforation and postoperative bleeding. In order to overcome such difficulties, we developed a scissors-type grasping device and reported the treatment results of a multicenter study. The aim of the present study was to investigate therapeutic outcomes of colorectal ESD of different tumor sizes.
  
  
  METHODS
  Group A (134 tumors): tumor size < 50 mm, and Group B (16 tumors): tumors ≥ 50 mm. All tumors were removed by ESD. We retrospectively evaluated the clinicopathological features of the tumors and the treatment results.
  
  
  RESULTS
  Age, sex, tumor location and histopathological diagnosis were not different between the two groups. Laterally spreading tumor non-granular type was more often observed in Group A (64/134, 47.8%) than in Group B (0/16, 0%). Procedure time was significantly longer in Group B (Group A: 38 min; Group B: 86 min, P < 0.01). However, procedure speed was significantly faster in Group B (Group A: 0.21 cm(2) /min; Group B: 0.37 cm(2) /min, P < 0.01). No complications were observed in either group. The en bloc resection rate, en bloc R0 resection rate, and en bloc curative resection rate were similar between the groups with no significant differences.
  
  
  CONCLUSIONS
  Procedure speed for Group B was faster than that for Group A. Group B was treated as safely as Group A.
authors.affiliation: Department of Therapeutic Endoscopy, Nihonkai General Hospital, Sakata, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Nawata
authors.forename: Kiyoaki
authors.initials: K
authors.lastname: Homma
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Suzuki
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003113:Colonoscopy / Q000009:adverse effects / Q000379:methods*; D015179:Colorectal Neoplasms / Q000473:pathology / Q000601:surgery*; D004210:Dissection / Q000009:adverse effects / Q000379:methods*; D005260:Female; D006801:Humans; D007413:Intestinal Mucosa / Q000473:pathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D016896:Treatment Outcome
keywords: bleeding; colorectal tumor; endoscopic submucosal dissection (ESD); perforation; procedure speed