title: Factors related to lateral margin positivity for cancer in gastric specimens of endoscopic submucosal dissection.
abstract: BACKGROUND
  With the widespread use of endoscopic submucosal dissection (ESD), more large early gastric cancers (EGC) have become candidates for endoscopic resection. A precise diagnosis of the extent of cancer is indispensable to obtain R0 resection. The aim of the present study was to clarify the factors related to lateral margin positivity for cancer in specimens resected by ESD for EGC.
  
  
  METHODS
  Among 1549 EGC treated by ESD during September 2002 to December 2008, lesions that were resected in an en-bloc fashion and resulted in a pathological diagnosis of lateral margin positive (LM+) for cancer, were extracted. The reason for LM+ and pathological characteristics of the lesions were studied and compared to lesions successfully resected with margins negative for cancer.
  
  
  RESULTS
  There were three types of lesion that resulted in LM+ resection: lesions with a flat spreading area, lesions with an unexpected nearby lesion, and lesions with lateral extension beneath a non-cancerous mucosa. Compared to lesions resected with margins negative for cancer, diameter of the tumor, recurrent-type cancer, submucosal cancer, and undifferentiated-type cancer were factors significantly related to LM+ resection.
  
  
  CONCLUSIONS
  Other than misdiagnosing a small portion of cancer extension, lateral margin positivity for cancer by ESD could result from a neighboring lesion and an unexpected lateral submucosal cancer extension. To avoid LM+ resection of EGC by ESD, one should be careful of unexpected lateral extension and simultaneous multi-lesions.
authors.affiliation: Division of Endoscopy, Shizuoka Cancer Center, Suntougun, Shizuoka, Japan. kakushin-tky@umin.ac.jp
authors.forename: Naomi
authors.initials: N
authors.lastname: Kakushima
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ono
authors.forename: Masaki
authors.initials: M
authors.lastname: Tanaka
authors.forename: Kohei
authors.initials: K
authors.lastname: Takizawa
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Yamaguchi
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Matsubayashi
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology* / Q000601:surgery; D004210:Dissection / Q000379:methods*; D042241:Early Diagnosis; D016099:Endoscopy, Gastrointestinal / Q000379:methods*; D005753:Gastric Mucosa / Q000473:pathology / Q000601:surgery*; D006801:Humans; D009367:Neoplasm Staging; D012189:Retrospective Studies; D013274:Stomach Neoplasms / Q000473:pathology* / Q000601:surgery