title: Outcomes of endoscopic submucosal dissection for differentiated-type early gastric cancer with histological heterogeneity.
abstract: BACKGROUND
  Long-term clinical outcomes after endoscopic submucosal dissection (ESD) is unclear for differentiated-type-predominant early gastric cancer (EGC) mixed with undifferentiated component (MUC-EGC). Therefore, the role and appropriate indication of ESD for MUC-EGC remain to be evaluated.
  
  
  METHODS
  Between 2007 and 2011, 1,577 differentiated-type EGC lesions [1,408 pure differentiated-type (PuD)-EGCs and 169 MUC-EGCs] in 1,527 consecutive patients were treated by ESD. After ESD, MUC-EGC was managed in the same way as PuD-EGC. The clinicopathological features and long-term outcomes after ESD of MUC-EGC were compared with those of PuD-EGC.
  
  
  RESULTS
  En bloc resection and en bloc with R0 resection rates in MUC-EGC cases were 94.1 % and 81.7 %, respectively. MUC-EGC was significantly associated with larger tumor size, more frequent submucosal invasion, and lymphovascular invasion compared to PuD-EGC. Despite these aggressive features of MUC-EGC, no lymph node metastasis or extragastric recurrence occurred during follow-up after ESD if MUC-EGC met the curative endoscopic resection (ER) criteria for tumors of absolute or expanded indications. Four MUC-EGC cases meeting the curative ER criteria underwent additional radical gastrectomy after ESD, and no case showed lymph node metastasis. During a median 48 months of follow-up, overall survival rates for MUC-EGC meeting the curative ER criteria for tumors of absolute or expanded indications (3-year survival rates, 100 % and 100 %) were comparable to those of PuD-EGC.
  
  
  CONCLUSIONS
  Long-term outcomes after ESD were favorable for MUC-EGCs meeting the curative ER criteria for tumors of absolute or expanded indications. Therefore, ESD may be used as a promising treatment option for these cases.
authors.affiliation: Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Irwon-dong, Gangnam-gu, Seoul, 135-710, Korea.
authors.forename: Byung-Hoon
authors.initials: BH
authors.lastname: Min
authors.forename: Kyoung-Mee
authors.initials: KM
authors.lastname: Kim
authors.forename: Cheol Keun
authors.initials: CK
authors.lastname: Park
authors.forename: Jun Haeng
authors.initials: JH
authors.lastname: Lee
authors.forename: Poong-Lyul
authors.initials: PL
authors.lastname: Rhee
authors.forename: Jong Chul
authors.initials: JC
authors.lastname: Rhee
authors.forename: Jae J
authors.initials: JJ
authors.lastname: Kim
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004210:Dissection; D055088:Early Detection of Cancer / Q000379:methods; D005260:Female; D005753:Gastric Mucosa / Q000473:pathology / Q000601:surgery; D005773:Gastroscopy; D006801:Humans; D053208:Kaplan-Meier Estimate; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D013274:Stomach Neoplasms / Q000401:mortality* / Q000473:pathology* / Q000628:therapy