title: Prognostic impact of the current Japanese nodal classification on outcomes in resected non-small cell lung cancer.
abstract: BACKGROUND
  The prognosis of N2 non-small cell lung cancer (NSCLC) has been reported to be heterogeneous. The recently revised Japanese nodal classification subcategorizes N2 disease according to the tumor-bearing lobe. We evaluated the prognostic impact of the Japanese nodal classification and its ability to define favorable N2 disease in resected NSCLC.
  
  
  METHODS
  A total of 496 patients with NSCLC who underwent lobectomy with systematic lymph node dissection between 1998 and 2009 were analyzed retrospectively. N2 status was subdivided into N2a-1 and N2a-2, according to the Japanese nodal classification. Overall survival (OS), disease-free survival (DFS), and clinicopathologic features were compared between the two groups.
  
  
  RESULTS
  There were 67 cases with N2 disease. The outcome of resected N2a-2 NSCLC was far poorer than that of the N2a-1 group (5-year OS, 28% vs 62%, P < .001; 5-year DFS, 5% vs 35%, P < .001). Multivariate analysis revealed that pathologic N2a-2 was an independent prognostic factor (hazard ratio, 2.86; P < .05). Patients in the N2a-2 group showed more involved nodes and stations, less skip metastasis, and more locoregional recurrence than did patients in the N2a-1 group. The outcome of the N2a-1 group was satisfactory, and there was no significant difference in OS and DFS between N1 and N2a-1.
  
  
  CONCLUSIONS
  The Japanese nodal classification is able to identify a favorable N2 subgroup in resected NSCLC. Nodal staging by the Japanese system should be considered when a clinical trial of N2 disease is designed.
authors.affiliation: Department of Thoracic Surgery, Graduate School of Medicine, University of Tokyo, Tokyo, Japan.
authors.forename: Junji
authors.initials: J
authors.lastname: Ichinose
authors.affiliation: Department of Thoracic Surgery, Graduate School of Medicine, University of Tokyo, Tokyo, Japan. Electronic address: murakawa-tky@umin.ac.jp.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Murakawa
authors.affiliation: Department of Thoracic Surgery, Graduate School of Medicine, University of Tokyo, Tokyo, Japan.
authors.forename: Haruaki
authors.initials: H
authors.lastname: Hino
authors.affiliation: Department of Thoracic Surgery, Graduate School of Medicine, University of Tokyo, Tokyo, Japan.
authors.forename: Chihiro
authors.initials: C
authors.lastname: Konoeda
authors.affiliation: Department of Thoracic Surgery, Graduate School of Medicine, University of Tokyo, Tokyo, Japan.
authors.forename: Yuta
authors.initials: Y
authors.lastname: Inoue
authors.affiliation: Department of Thoracic Surgery, Graduate School of Medicine, University of Tokyo, Tokyo, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Kitano
authors.affiliation: Department of Thoracic Surgery, Graduate School of Medicine, University of Tokyo, Tokyo, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Nagayama
authors.affiliation: Department of Thoracic Surgery, Graduate School of Medicine, University of Tokyo, Tokyo, Japan.
authors.forename: Jun-Ichi
authors.initials: JI
authors.lastname: Nitadori
authors.affiliation: Department of Thoracic Surgery, Graduate School of Medicine, University of Tokyo, Tokyo, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Anraku
authors.affiliation: Department of Thoracic Surgery, Graduate School of Medicine, University of Tokyo, Tokyo, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Nakajima
mesh_terms: D000368:Aged; D002289:Carcinoma, Non-Small-Cell Lung / Q000145:classification* / Q000401:mortality / Q000473:pathology*; D005260:Female; D006801:Humans; D007564:Japan; D053208:Kaplan-Meier Estimate; D008175:Lung Neoplasms / Q000145:classification* / Q000401:mortality / Q000473:pathology*; D008197:Lymph Node Excision; D008198:Lymph Nodes / Q000473:pathology* / Q000601:surgery; D008207:Lymphatic Metastasis / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D012189:Retrospective Studies; D015996:Survival Rate