title: Treatment strategy for laterally spreading tumors in Japan: before and after the introduction of endoscopic submucosal dissection.
abstract: OBJECTIVE
  Laterally spreading tumors (LST) in the colorectum are considered good candidates for endoscopic resection (ER). Because LST-non-granular (NG) tumors show multifocal invasion into the submucosal layer, en bloc resection is necessary for adequate histopathological evaluation. Therefore, surgical resection has been recommended when a lesion is suspected to be an invasive cancer and too large to resect en bloc. The aim of the present study was to evaluate whether the introduction of colorectal ESD, which was developed for en bloc resection of early gastric cancers, could improve the en bloc resection rate of large LST-NG-type tumors and reduce the surgical resection rate.
  
  
  METHODS
  Between January 1999 and December 2005, a total of 166 LST-NG-type tumors measuring > or = 20 mm in 161 patients were included in this study. The en bloc resection rate and the surgical resection rate were historically compared between two periods, before and after the introduction of ESD.
  
  
  RESULTS
  The en bloc resection rate for ER lesions was significantly higher in the latter period (35.0% [14/40]vs 76.5% [75/98]; P < 0.001), and the rate of surgery for adenomas and intramucosal or sm minute cancers was significantly lower in the latter period (20.0% [10/50]vs 1.1% [1/89]; P < 0.001).
  
  
  CONCLUSIONS
  The introduction of colonic ESD was able to change our treatment strategy for LST, improving the en bloc resection rate and reducing the surgical resection rate.
authors.affiliation: Division of Endoscopy, National Cancer Center Hospital, Tokyo, Japan. nkobayas@tcc.pref.tochigi.lg.jp
authors.forename: Nozomu
authors.initials: N
authors.lastname: Kobayashi
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Saito
authors.forename: Toshio
authors.initials: T
authors.lastname: Uraoka
authors.forename: Takahisa
authors.initials: T
authors.lastname: Matsuda
authors.forename: Haruhisa
authors.initials: H
authors.lastname: Suzuki
authors.forename: Takahiro
authors.initials: T
authors.lastname: Fujii
mesh_terms: D000236:Adenoma / Q000473:pathology / Q000601:surgery*; D002983:Clinical Competence; D003082:Colectomy; D003113:Colonoscopy / Q000009:adverse effects; D015179:Colorectal Neoplasms / Q000473:pathology / Q000601:surgery*; D006801:Humans; D007413:Intestinal Mucosa / Q000473:pathology / Q000601:surgery*; D007564:Japan; D009361:Neoplasm Invasiveness; D018579:Patient Selection; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome