title: Predictive factors for technically difficult endoscopic submucosal dissection in the colorectum.
abstract: OBJECTIVE
  Because of technical difficulty, colorectal endoscopic submucosal dissection (CR-ESD) is not widely performed. We aimed to determine risk factors for such technical difficulty as defined by long procedure duration (≥  150 min), perforation, and piecemeal resection.
  
  
  METHODS
  Patients with consecutive colorectal tumors treated with ESD between April 2006 and December 2010 were enrolled in a prospective cohort study. For prediction of technical difficulty, three types of factor were investigated: tumor location, tumor type, and colonoscopy-related. Cases were subsequently categorized into earlier and later periods (April 2006 - August 2008, 123 lesions; September 2008 - December 2010, 124 lesions). Variables were analyzed using multiple logistic regression, with subgroup analyses for each period.
  
  
  RESULTS
  247 lesions were analyzed. Flexure location was an independent risk factor for technical difficulty as measured by longer procedure duration (odds ratio [OR] 4.1, 95 % confidence interval [95 %CI] 1.1 - 14.9), piecemeal resection (4.7, 1.1 - 17.2), or perforation (8.8, 1.1 - 56.8). Tumor with scarring or locally recurrent was a risk factor for longer procedure duration (4.7, 1.7 - 13.7), and for piecemeal resection (7.8, 2.4 - 25.0). Tumor of size  ≥  50 mm or spreading across ≥  2 folds was the strongest independent risk factor for longer duration (6.3, 2.8 - 15.4), and was an independent risk factor for longer duration in both time periods (earlier, 3.3, 1.1 - 10.4; later, 27.4, 7.4 - 138.0). Flexure location was an independent risk factor for perforation (13.9, 1.5 - 129.1) and for piecemeal resection (5.1, 0.9 - 25.2) in the earlier but not the later period.
  
  
  CONCLUSIONS
  Factors predicting technical difficulty of CR-ESDs were clarified. Their importance was influenced by the increasing experience of the endoscopist.
authors.affiliation: Department of Endoscopy, Okayama University Hospital, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Hori
authors.affiliation: Department of Endoscopy, Okayama University Hospital, Japan.
authors.forename: Toshio
authors.initials: T
authors.lastname: Uraoka
authors.affiliation: Department of Endoscopy, Okayama University Hospital, Japan.
authors.forename: Keita
authors.initials: K
authors.lastname: Harada
authors.affiliation: Department of Internal Medicine, Hiroshima City Hospital, Japan.
authors.forename: Reiji
authors.initials: R
authors.lastname: Higashi
authors.affiliation: Department of Endoscopy, Okayama University Hospital, Japan.
authors.forename: Yoshiro
authors.initials: Y
authors.lastname: Kawahara
authors.affiliation: Department of Endoscopy, Okayama University Hospital, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Okada
authors.affiliation: University of Tennessee College of Medicine, Academic Gastroenterology, Program in Advanced Therapeutic and Interventional Endoscopy, Erlanger Hospital, Chattanooga, Tennessee, USA.
authors.forename: Hemchand
authors.initials: H
authors.lastname: Ramberan
authors.affiliation: Division of Research and Development for Minimally Invasive Treatment, Cancer Center, School of Medicine, Keio University, Tokyo, Japan.
authors.forename: Naohisa
authors.initials: N
authors.lastname: Yahagi
authors.affiliation: Department of Gastroenterology and Hepatology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Japan.
authors.forename: Kazuhide
authors.initials: K
authors.lastname: Yamamoto
mesh_terms: D000368:Aged; D002921:Cicatrix / Q000601:surgery; D044684:Colon, Transverse / Q000473:pathology; D003113:Colonoscopy / Q000009:adverse effects*; D015179:Colorectal Neoplasms / Q000473:pathology* / Q000601:surgery*; D004210:Dissection / Q000009:adverse effects*; D005260:Female; D006801:Humans; D007413:Intestinal Mucosa / Q000601:surgery*; D007416:Intestinal Perforation / Q000209:etiology*; D059032:Learning Curve; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000601:surgery*; D061646:Operative Time; D011446:Prospective Studies; D012307:Risk Factors; D047368:Tumor Burden