title: Risk of lymph node metastasis in differentiated type mucosal early gastric cancer mixed with minor undifferentiated type histology.
abstract: BACKGROUND
  The possibility of lymph node metastasis is critical to the assessment of the indication for endoscopic submucosal dissection. The differentiation of tumors is an important predicting factor for lymph node metastasis. Even though gastric cancers frequently show intratumoral heterogeneity, most studies have not considered the effects of the minor histologic components. The purpose of this study was to investigate the relationship between the presence of undifferentiated type histology (UD-min) within differentiated type tumors and lymph node metastases in early gastric cancer confined to the mucosal layer.
  
  
  METHODS
  A retrospective study of 847 patients who underwent surgery for differentiated early gastric cancer, confined to mucosa, was conducted. We analyzed the proportion of the undifferentiated type components of the tumor and their relationship with lymph node metastasis.
  
  
  RESULTS
  The overall rate of lymph node metastasis was 1.7 % (14/847 patients) and 215 differentiated tumors (25.4 %) have UD-min. UD-min was associated with female sex, younger age, larger tumor size, and the presence of ulcer. Lymph node metastasis rate with or without UD-min was 5.1 % (11/215) versus 0.5 % (3/632), respectively (p < 0.001). UD-min was found to be associated with lymph node metastasis in the multivariate analyses (odds ratio [OR] = 4.39, CI 1.08-17.89). When three risk factors (tumor size >2 cm, ulcer, and UD-min) were present concurrently, the rate of lymph node metastasis was high (10 %).
  
  
  CONCLUSIONS
  The presence of an UD-min component should be considered when assessing curative resection status of endoscopic submucosal dissection for differentiated type mucosal cancer.
authors.affiliation: Center for Gastric Cancer/Department of Pathology, National Cancer Center, Goyang-si, Gyeonggi-do, Republic of Korea.
authors.forename: Jun Ho
authors.initials: JH
authors.lastname: Lee
authors.forename: Il Ju
authors.initials: IJ
authors.lastname: Choi
authors.forename: Hye Seung
authors.initials: HS
authors.lastname: Han
authors.forename: Young-Woo
authors.initials: YW
authors.lastname: Kim
authors.forename: Keun Won
authors.initials: KW
authors.lastname: Ryu
authors.forename: Hong Man
authors.initials: HM
authors.lastname: Yoon
authors.forename: Bang Wool
authors.initials: BW
authors.lastname: Eom
authors.forename: Chan Gyoo
authors.initials: CG
authors.lastname: Kim
authors.forename: Jong Yeul
authors.initials: JY
authors.lastname: Lee
authors.forename: Soo-Jeong
authors.initials: SJ
authors.lastname: Cho
authors.forename: Young-Il
authors.initials: YI
authors.lastname: Kim
authors.forename: Byung-Ho
authors.initials: BH
authors.lastname: Nam
authors.forename: Myeong-Cherl
authors.initials: MC
authors.lastname: Kook
mesh_terms: D000230:Adenocarcinoma / Q000556:secondary* / Q000601:surgery; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002454:Cell Differentiation; D055088:Early Detection of Cancer; D005260:Female; D005500:Follow-Up Studies; D005743:Gastrectomy / Q000009:adverse effects*; D005753:Gastric Mucosa / Q000473:pathology*; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D011183:Postoperative Complications; D011379:Prognosis; D012189:Retrospective Studies; D012307:Risk Factors; D013274:Stomach Neoplasms / Q000473:pathology* / Q000601:surgery