title: Prognostic impact of number of resected and involved lymph nodes at complete resection on survival in non-small cell lung cancer.
abstract: BACKGROUND
  Lymph node (LN) status is a major determinant of stage and survival in patients with lung cancer. In the 7th edition of the TNM Classification of Malignant Tumors, the number of involved LNs is included in the definition of pN factors in breast, stomach, esophageal, and colorectal cancer, and the pN status significantly correlates with prognosis.
  
  
  METHODS
  We retrospectively investigated the prognostic impact of the number of resected LNs (RLNs) and involved LNs in the context of other established clinical prognostic factors, in a series of 928 consecutive patients with non-small cell lung cancer (NSCLC) who underwent complete resection at our institution between 2000 and 2007.
  
  
  RESULTS
  The mean number of RLNs was 15. There was a significant difference in the total number of RLNs categorized between less than 10 and ≥10 (p = 0.0129). Although the incidence of LN involvement was statistically associated with poor prognosis, the largest statistically significant increase in overall survival was observed between 0 to 3 and ≥4 involved LNs (hazard ratio = 7.680; 95% confidence interval = 5.051-11.655, p < 0.0001). On multivariate analysis, we used the ratio between the number of involved LNs and RLNs. The number of RLNs was found to be a strong independent prognostic factor for NSCLC (hazard ratio = 6.803; 95% confidence interval = 4.137-11.186, p < 0.0001).
  
  
  CONCLUSIONS
  Complete resection including 10 or more LNs influenced survival at complete NSCLC resection. Four involved LNs seemed to be a benchmark for NSCLC prognosis. The number of involved LNs is a strong independent prognostic factor in NSCLC, and the results of this study may provide new information for determining the N category in the next tumor, node, metastasis classification.
authors.affiliation: Division of Thoracic Surgery, Department of Surgery, Tokyo Medical University, Shinjuku-ku, Tokyo, Japan. saji-q@ya2.so-net.ne.jp
authors.forename: Hisashi
authors.initials: H
authors.lastname: Saji
authors.forename: Masahiro
authors.initials: M
authors.lastname: Tsuboi
authors.forename: Koichi
authors.initials: K
authors.lastname: Yoshida
authors.forename: Yasufumi
authors.initials: Y
authors.lastname: Kato
authors.forename: Masaharu
authors.initials: M
authors.lastname: Nomura
authors.forename: Jun
authors.initials: J
authors.lastname: Matsubayashi
authors.forename: Toshitaka
authors.initials: T
authors.lastname: Nagao
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Kakihana
authors.forename: Jitsuo
authors.initials: J
authors.lastname: Usuda
authors.forename: Naohiro
authors.initials: N
authors.lastname: Kajiwara
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Ohira
authors.forename: Norihiko
authors.initials: N
authors.lastname: Ikeda
mesh_terms: D000230:Adenocarcinoma / Q000401:mortality* / Q000473:pathology / Q000601:surgery; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018287:Carcinoma, Large Cell / Q000401:mortality* / Q000473:pathology / Q000601:surgery; D002289:Carcinoma, Non-Small-Cell Lung / Q000401:mortality* / Q000473:pathology / Q000601:surgery; D002294:Carcinoma, Squamous Cell / Q000401:mortality* / Q000473:pathology / Q000601:surgery; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008175:Lung Neoplasms / Q000401:mortality* / Q000473:pathology / Q000601:surgery; D008198:Lymph Nodes / Q000473:pathology* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D012189:Retrospective Studies; D015996:Survival Rate; D055815:Young Adult