title: Metastatic lymph node ratio as a prognostic factor after laparoscopic total mesorectal excision for extraperitoneal rectal cancer.
abstract: BACKGROUND
  The lymph node ratio (LNR; number of positive nodes divided by total nodes harvested) has been demonstrated to be a prognostic factor in colon cancer, but its role in extraperitoneal rectal cancer is still debated; furthermore, no data are available on laparoscopic rectal resection. The aim of this study was to evaluate the prognostic impact of LNR on long-term outcomes after laparoscopic total mesorectal excision (LTME) for extraperitoneal cancer in consecutive patients with a 5-year minimum follow-up.
  
  
  METHODS
  This study is a prospective analysis of consecutive patients who underwent LTME for adenocarcinoma of the extraperitoneal rectum.
  
  
  RESULTS
  LTME was performed in 158 patients. The median number of LN harvested was 12 (range = 3-25). The proportion of specimens with fewer than 12 examined LN was significantly higher in patients who had neoadjuvant chemoradiotherapy (p < 0.001). During a median follow-up period of 122 months, the local recurrence rate was 8 %. At univariate analysis, disease-free survival and overall survival significantly decreased with increasing LNR (p < 0.001). Multivariate analysis showed that the distal margin ≤ 1 cm was the only independent predictor of local recurrence (p = 0.028). LNR (cutoff value = 0.25) and lymphovascular invasion were significant prognostic factors for both disease-free (p = 0.015 and p = 0.046, respectively) and overall survival (p = 0.031 and p = 0.040, respectively). Even in the subgroup of patients in whom fewer than 12 LN were examined, LNR confirmed its prognostic role, with a statistical trend toward worse disease-free survival and overall survival.
  
  
  CONCLUSIONS
  Metastatic LNR is an independent prognostic factor for disease-free survival and overall survival after LTME for extraperitoneal rectal cancer.
authors.affiliation: Digestive, Colorectal, Oncologic and Minimally Invasive Surgery, Department of Surgical Sciences, University of Torino, Corso A. M. Dogliotti 14, 10126, Turin, Italy. marcoettore_allaix@yahoo.it
authors.forename: Marco Ettore
authors.initials: ME
authors.lastname: Allaix
authors.forename: Alberto
authors.initials: A
authors.lastname: Arezzo
authors.forename: Paola
authors.initials: P
authors.lastname: Cassoni
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Mistrangelo
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Giraudo
authors.forename: Mario
authors.initials: M
authors.lastname: Morino
mesh_terms: D000230:Adenocarcinoma / Q000401:mortality / Q000473:pathology* / Q000601:surgery*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D061887:Conversion to Open Surgery / Q000401:mortality / Q000706:statistics & numerical data; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D010535:Laparoscopy / Q000379:methods* / Q000401:mortality; D008197:Lymph Node Excision / Q000379:methods / Q000401:mortality; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000209:etiology / Q000401:mortality / Q000473:pathology; D011379:Prognosis; D011446:Prospective Studies; D012004:Rectal Neoplasms / Q000401:mortality / Q000473:pathology / Q000601:surgery*; D012307:Risk Factors