title: Process of distant lymph node metastasis in colorectal carcinoma: implication of extracapsular invasion of lymph node metastasis.
abstract: BACKGROUND
  We previously demonstrated that extracapsular invasion (ECI) at a metastatic sentinel node was significantly associated with the presence of positive non-sentinel nodes in patients with breast cancer. However, the mechanism of metastatic spreading of tumor cells to distant lymph nodes in patients with colorectal carcinoma is not fully understood. In this study, we investigated the factors that may determine the likelihood of additional regional lymph node metastasis when metastasis is found in nodes at the N1 site in colorectal cancer, especially focusing on the presence of ECI.
  
  
  METHODS
  Two hundred and twenty-eight consecutive patients who underwent colorectal resection were identified for inclusion in this study, of which 37 (16.2%) had positive lymph nodes at the N1 site. Six of these 37 cases had additional metastasis in N2 site lymph nodes. We reviewed the clinicopathological features of these cases and performed statistical analysis of the data.
  
  
  RESULTS
  In the univariate analysis ECI at the N1 site was the only factor significantly associated with the presence of cancer cells in the N2 site. Other factors, including number of positive lymph nodes, lymphovascular invasion of the primary tumor, tumor size and tumor depth of invasion, were not associated with metastatic involvement at the N2 site.
  
  
  CONCLUSIONS
  Our results suggest that the presence of ECI at metastatic lymph nodes at the N1 site is correlated with further metastasis at the N2 site. These findings imply the possibility that ECI might indicate the ability of colorectal tumor cells to disseminate to distant lymph nodes.
authors.affiliation: Department of General Surgical Science, Graduate School of Medicine, Gunma University, (Showa-machi, Maebashi), Gunma, Japan. ftakaaki@med.gunma-u.ac.jp
authors.forename: Takaaki
authors.initials: T
authors.lastname: Fujii
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Tabe
authors.forename: Reina
authors.initials: R
authors.lastname: Yajima
authors.forename: Satoru
authors.initials: S
authors.lastname: Yamaguchi
authors.forename: Soichi
authors.initials: S
authors.lastname: Tsutsumi
authors.forename: Takayuki
authors.initials: T
authors.lastname: Asao
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kuwano
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015179:Colorectal Neoplasms / Q000473:pathology*; D005260:Female; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009361:Neoplasm Invasiveness