title: Prognostic impact of lymph node harvest and lymph node ratio in patients with colon cancer.
abstract: BACKGROUND
  The prognostic impact of the number of lymph nodes and ratio in colon cancer is still debated.
  
  
  OBJECTIVE
  The aim of this study was to evaluate lymph node harvest in patients with colon cancer over time, and to test the hypotheses that investigation of more lymph nodes, and low lymph node ratio in stage III patients, has positive prognostic impact.
  
  
  METHODS
  This is a prospective, observational study.
  
  
  METHODS
  This study was conducted in a single institution treating all patients with colon cancer in a defined catchment area.
  
  
  METHODS
  All patients admitted in the period 1993 to 2009 (n = 1481) were included.
  
  
  METHODS
  The primary outcomes measured were the number of examined regional lymph nodes according to treatment period, 5-year overall survival and time to recurrence, and univariate (Kaplan-Meier) and multivariate (Cox regression) analyses of prognostic factors.
  
  
  RESULTS
  Nine hundred fifty (65%) patients underwent curative resection. Median number of examined lymph nodes increased from 7 to 15 (p < 0.001), and the proportion of patients with stage III disease increased from 25% to 33% (p = 0.02) during the study period. In patients with stage I to III disease, time to recurrence (proportion of patients without recurrence or death of colon cancer) improved from 65% to 82% during the period (p < 0.001). An association between lymph node count (<8 compared with ≥ 12) and overall survival was found for patients with stage II disease (57% vs 71%, p = 0.004). Hazard ratio for death within 5 years was 0.7 (p = 0.043) when 8 to 11 nodes were examined and 0.6 (p = 0.001) when ≥ 12 nodes were examined (<8 reference). In patients with stage III disease, increasing lymph node ratio was associated with reduced overall survival and time to recurrence in uni- and multivariate analyses.
  
  
  CONCLUSIONS
  This study was limited by the small number of patients in each stage.
  
  
  CONCLUSIONS
  The number of examined lymph nodes increased in the study period. A stage migration was observed, and time to recurrence improved in patients with stage I to III disease. In patients with stage III disease, lymph node ratio was a stronger prognostic factor than the total number of lymph nodes examined.
authors.affiliation: Department of Gastrointestinal Surgery, Oslo University Hospital Aker, Oslo, Norway. ole.h.sjo@c2i.net
authors.forename: Ole H
authors.initials: OH
authors.lastname: Sjo
authors.forename: Marianne A
authors.initials: MA
authors.lastname: Merok
authors.forename: Aud
authors.initials: A
authors.lastname: Svindland
authors.forename: Arild
authors.initials: A
authors.lastname: Nesbakken
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology / Q000601:surgery*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003110:Colonic Neoplasms / Q000401:mortality / Q000473:pathology / Q000601:surgery*; D005260:Female; D006801:Humans; D008197:Lymph Node Excision; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D015996:Survival Rate