title: Low Incidence of Synchronous or Metachronous Tumors after Endoscopic Submucosal Dissection for Early Gastric Cancer with Undifferentiated Histology.
abstract: BACKGROUND
  Gastric cancer with undifferentiated histology has different clinicopathologic characteristics compared to differentiated type gastric cancer. We aimed to compare the risk of synchronous or metachronous tumors after curative resection of early gastric cancer (EGC) via endoscopic submucosal dissection (ESD), according to the histologic differentiation of the primary lesion.
  
  
  METHODS
  Clinicopathological data of patients with initial-onset EGC curatively resected via ESD between January 2007 and November 2014 in a single institution were reviewed. We analyzed the incidence of synchronous or metachronous tumors after ESD with special reference to the differentiation status of the primary lesion.
  
  
  RESULTS
  Of 1,560 patients with EGC who underwent curative resection via ESD, 1,447 had differentiated type cancers, and 113 had undifferentiated type cancers. The cumulative incidence of metachronous or synchronous tumor after ESD was higher in the differentiated cancer group than in the undifferentiated cancer group (P = 0.008). Incidence of metachronous or synchronous tumor was 4.8% and 1.2% per person-year in the differentiated and undifferentiated cancer groups, respectively. The Cox proportional hazard model revealed that undifferentiated cancers were associated with a low risk of synchronous or metachronous tumors after adjusting for confounding variables (hazard ratio [95% confidence interval] = 0.287 [0.090-0.918]).
  
  
  CONCLUSIONS
  The rate of synchronous or metachronous tumors after curative ESD was significantly lower for undifferentiated cancers compare to differentiated cancers. These findings suggest that ESD should be actively considered as a possible treatment for undifferentiated type EGCs.
authors.affiliation: Department of Internal Medicine, Guri Hospital, Hanyang University College of Medicine, Guri, Korea.
authors.forename: Chan Hyuk
authors.initials: CH
authors.lastname: Park
authors.affiliation: Division of Gastroenterology, Department of Internal Medicine, Severance Hospital, Institute of Gastroenterology, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Eun Hye
authors.initials: EH
authors.lastname: Kim
authors.affiliation: Division of Gastroenterology, Department of Internal Medicine, Severance Hospital, Institute of Gastroenterology, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Jung Hyun
authors.initials: JH
authors.lastname: Kang
authors.affiliation: Division of Gastroenterology, Department of Internal Medicine, Severance Hospital, Institute of Gastroenterology, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Hyunsoo
authors.initials: H
authors.lastname: Chung
authors.affiliation: Division of Gastroenterology, Department of Internal Medicine, Severance Hospital, Institute of Gastroenterology, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Jun Chul
authors.initials: JC
authors.lastname: Park
authors.affiliation: Division of Gastroenterology, Department of Internal Medicine, Severance Hospital, Institute of Gastroenterology, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Sung Kwan
authors.initials: SK
authors.lastname: Shin
authors.affiliation: Division of Gastroenterology, Department of Internal Medicine, Severance Hospital, Institute of Gastroenterology, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Sang Kil
authors.initials: SK
authors.lastname: Lee
authors.affiliation: Division of Gastroenterology, Department of Internal Medicine, Severance Hospital, Institute of Gastroenterology, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Yong Chan
authors.initials: YC
authors.lastname: Lee
mesh_terms: D000368:Aged; D055088:Early Detection of Cancer; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013274:Stomach Neoplasms / Q000453:epidemiology* / Q000601:surgery*
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