title: Skip mediastinal nodal metastases in non-small cell lung cancer.
abstract: OBJECTIVE
  To reveal the incidence and clinical significance of mediastinal nodal metastases without N1-station nodal metastases ('skip-N2 metastases') in non-small cell lung cancer (NSCLC).
  
  
  METHODS
  A total of 450 NSCLC patients who underwent tumor resection with a systemic mediastinal nodal dissection were retrospectively reviewed. p53 status and proliferative activity represented as proliferative index (PI) were also examined immunohistochemically.
  
  
  RESULTS
  Skip-N2 metastases were documented in 49 (13%) patients of all 450 patients; among 334 patients without N1-nodal involvement, 18% patients had skip-N2 metastases. The postoperative survival of skip-N2 patients was almost same as that for patients with metastases to both N1 and N2 nodes. Skip-N2 metastases were significantly more frequent in male patients and squamous cell carcinoma patients. In addition, the mean PI for tumor with skip-N2 metastases was significantly higher than that for any other pathologic nodal (pN)-status diseases. Combined with histologic type and PI, the incidences of skip-N2 metastases for adenocarcinoma showing lower PI were only 5% (7/137) of all patients and 7% (7/94) of patients without N1-nodal involvement.
  
  
  CONCLUSIONS
  N1 nodal status is not a useful predictor of N2 nodal status in NSCLC, because skip-N2 metastases were documented in 18% patients showing no N1-nodal involvement. However, N1 node-guided dissection might be performed in patients with adenocarcinoma showing lower PI, because the incidence of skip-N2 metastases was extremely low.
authors.affiliation: Department of Thoracic Surgery, Faculty of Medicine, Kyoto University, Shogoin-kawahara-cho 54, Sakyo-ku, Kyoto 606-8507, Japan. ftanaka@kuhp.kyoto-u.ac.jp
authors.forename: Fumihiro
authors.initials: F
authors.lastname: Tanaka
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Takenaka
authors.forename: Hiroki
authors.initials: H
authors.lastname: Oyanagi
authors.forename: Takuji
authors.initials: T
authors.lastname: Fujinaga
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Otake
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Yanagihara
authors.forename: Harumi
authors.initials: H
authors.lastname: Ito
authors.forename: Hiromi
authors.initials: H
authors.lastname: Wada
mesh_terms: D000368:Aged; D002289:Carcinoma, Non-Small-Cell Lung / Q000473:pathology / Q000556:secondary* / Q000601:surgery; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology* / Q000601:surgery; D008207:Lymphatic Metastasis; D008297:Male; D008482:Mediastinum; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D012189:Retrospective Studies; D015996:Survival Rate; D016896:Treatment Outcome