title: The risk of lymph node metastasis in T1 colorectal carcinoma.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the risk of lymph node metastasis in patients with T1 colorectal carcinoma based on a uniform histopathology system, and to accomplish guidelines for additional surgery for endoscopically or locally removed T1 colorectal carcinoma.
  
  
  METHODS
  A review was performed of 301 patients who underwent curative resection for T1 colorectal carcinoma between January 1970 and March 2001. The following clinicopathologic variables were evaluated using univariate and multivariate analysis: sex, age, location, size of tumor, macroscopic appearance, depth of submucosal invasion, lymphovascular invasion, and histologic grade. Lesions were subdivided according to the depth of submucosal invasion: sm1, submucosal invasion up to 500 microm from the muscularis mucosa; sm2, submucosal invasion between 500 and 1000 microm; sm3, submucosal invasion beyond 1000 microm.
  
  
  RESULTS
  The overall lymph node metastasis rate was 6.3 per cent (19 of 301). Depth of submucosal invasion (sm3) and presence of lymphovascular invasion were significant risk factors for lymph node metastasis both univariately and multivariately.
  
  
  CONCLUSIONS
  The findings of the current study demonstrated that significant risk factors for lymph node metastasis were level of submucosal invasion (sm3) and the presence of lymphovascular invasion. Surgery is indicated for patients with adverse factors.
authors.affiliation: Department of Surgery, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Seiichiro
authors.initials: S
authors.lastname: Yamamoto
authors.forename: Masahiko
authors.initials: M
authors.lastname: Watanabe
authors.forename: Hirotoshi
authors.initials: H
authors.lastname: Hasegawa
authors.forename: Hideo
authors.initials: H
authors.lastname: Baba
authors.forename: Kentaro
authors.initials: K
authors.lastname: Yoshinare
authors.forename: Junichi
authors.initials: J
authors.lastname: Shiraishi
authors.forename: Masaki
authors.initials: M
authors.lastname: Kitajima
mesh_terms: D000368:Aged; D001808:Blood Vessels / Q000473:pathology; D003106:Colon / Q000098:blood supply / Q000473:pathology; D015179:Colorectal Neoplasms / Q000473:pathology; D005260:Female; D006801:Humans; D015994:Incidence; D007413:Intestinal Mucosa / Q000473:pathology; D016015:Logistic Models; D008198:Lymph Nodes / Q000473:pathology; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D012189:Retrospective Studies; D012307:Risk Factors