title: Early gastric cancer with mixed histology predominantly of differentiated type is a distinct subtype with different therapeutic outcomes of endoscopic resection.
abstract: BACKGROUND
  Safety of endoscopic resection (ER) for early gastric cancers (EGC) with mixed histology predominantly of differentiated type has not been securely established, since those lesions tend to exhibit lymph node metastasis, compared to pure differentiated type. The purpose of this study was to evaluate clinicopathologic characteristics, therapeutic outcomes, and risk for lymph node metastasis in predominantly differentiated mixed EGC treated by ER.
  
  
  METHODS
  A total of 1,016 patients with 1,039 EGCs underwent ER between January 2007 and June 2013. Enrolled lesions were divided into groups of either pure differentiated (n = 1,011) or predominantly differentiated mixed (n = 28), according to the presence of mixed histology predominantly of differentiated type in ER specimen.
  
  
  RESULTS
  Mixed histology predominantly of differentiated type was diagnosed in 2.7% of lesions. Larger size, mid-third location, and moderately differentiated histology on forceps biopsy were independent risk factors for the predominantly differentiated mixed histologic type of EGC in multivariate analysis. En bloc resection rate tended to be lower, and complete and curative resection rates were significantly lower in the predominantly differentiated mixed group. The rate of lymph node metastasis in the lesions with additional operation tended to be higher, in this mixed histology group.
  
  
  CONCLUSIONS
  Larger size, mid-third location, and moderately differentiated histology on forceps biopsy carry the significant risk for mixed histology predominantly of differentiated type. EGC with predominantly differentiated mixed histologic type affects therapeutic outcomes and consequent clinical course accompanied by possibly higher risk for lymph node metastasis. The safety of ER for predominantly differentiated mixed EGC should be validated by further prospective investigation.
authors.affiliation: Department of Internal Medicine, Institute of Gastroenterology, Yonsei University College of Medicine, 50 Yonsei-ro, Seodaemun-gu, Seoul, 120-752, Korea, kscn99@gmail.com.
authors.forename: Choong Nam
authors.initials: CN
authors.lastname: Shim
authors.forename: Hyunsoo
authors.initials: H
authors.lastname: Chung
authors.forename: Jun Chul
authors.initials: JC
authors.lastname: Park
authors.forename: Hyuk
authors.initials: H
authors.lastname: Lee
authors.forename: Sung Kwan
authors.initials: SK
authors.lastname: Shin
authors.forename: Sang Kil
authors.initials: SK
authors.lastname: Lee
authors.forename: Yong Chan
authors.initials: YC
authors.lastname: Lee
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis / Q000601:surgery*; D000368:Aged; D001706:Biopsy; D042241:Early Diagnosis; D016099:Endoscopy, Gastrointestinal / Q000379:methods*; D005260:Female; D005743:Gastrectomy / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D012189:Retrospective Studies; D013274:Stomach Neoplasms / Q000175:diagnosis / Q000601:surgery*