title: Is lower zone mediastinal nodal dissection always mandatory for lung cancer in the lower lobe?
abstract: OBJECTIVE
  Dissection of the lower zone mediastinal nodes is mandatory during systematic nodal dissection for lung cancer. However, the significance of lower zone lymph node metastasis (LZM) in lung cancer remains unclear. Therefore, we aimed to identify the predictive factors for LZM in patients with lower lobe lung cancer.
  
  
  METHODS
  A retrospective study was conducted on 257 patients with lower lobe lung cancer, in whom pulmonary resection and mediastinal nodal dissection were performed between 2009 and 2013. The radiological factors on thin-section computed tomography scans (TSCT) and several conventional clinical factors were evaluated as possible predictors of LZM.
  
  
  RESULTS
  Twenty (7.8 %) patients exhibited LZM. The majority of the tumors were especially located in segment 10 (50 %). All patients showed a solid appearance on TSCT. In a univariate analysis, the tumor location, a solid appearance and the clinical T factor significantly predicted LZM (p = 0.011, 0.005, 0.018). Furthermore, based on a multivariate analysis, the tumor location in segment 10 significantly predicted LZM in patients with lower lobe solid lung cancer (p = 0.031).
  
  
  CONCLUSIONS
  The appropriate surgical strategy for lower zone lymph node dissection should be selected based on the tumor location and the findings of TSCT, due to the high frequency of LZM (19.6 %), especially in patients with pure solid lung cancer in segment 10.
authors.affiliation: Department of General Thoracic Surgery, Juntendo University School of Medicine, 1-3, Hongo 3-chome, Bunkyo-ku, 113-8431, Tokyo, Japan. h-ueno@juntendo.ac.jp.
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Ueno
authors.affiliation: Department of General Thoracic Surgery, Juntendo University School of Medicine, 1-3, Hongo 3-chome, Bunkyo-ku, 113-8431, Tokyo, Japan.
authors.forename: Aritoshi
authors.initials: A
authors.lastname: Hattori
authors.affiliation: Department of General Thoracic Surgery, Juntendo University School of Medicine, 1-3, Hongo 3-chome, Bunkyo-ku, 113-8431, Tokyo, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Matsunaga
authors.affiliation: Department of General Thoracic Surgery, Juntendo University School of Medicine, 1-3, Hongo 3-chome, Bunkyo-ku, 113-8431, Tokyo, Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Takamochi
authors.affiliation: Department of General Thoracic Surgery, Juntendo University School of Medicine, 1-3, Hongo 3-chome, Bunkyo-ku, 113-8431, Tokyo, Japan.
authors.forename: Shiaki
authors.initials: S
authors.lastname: Oh
authors.affiliation: Department of General Thoracic Surgery, Juntendo University School of Medicine, 1-3, Hongo 3-chome, Bunkyo-ku, 113-8431, Tokyo, Japan. kjsuzuki@juntendo.ac.jp.
authors.forename: Kenji
authors.initials: K
authors.lastname: Suzuki
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000601:surgery*; D008197:Lymph Node Excision / Q000379:methods*; D008198:Lymph Nodes / Q000601:surgery*; D008297:Male; D008482:Mediastinum; D008875:Middle Aged; D011013:Pneumonectomy; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed
keywords: Lower zone lymph node; Lung cancer; Lymph node dissection; Predictive factor