title: Factors predicting occult lymph node metastasis in completely resected lung adenocarcinoma of 3 cm or smaller.
abstract: OBJECTIVE
  The aim of the study is to demonstrate the relationship between clinicopathological variables and occult lymph node metastasis in resected lung adenocarcinoma.
  
  
  METHODS
  The clinicopathological characteristics of 471 patients with clinical N2-negative status undergoing resection for lung adenocarcinoma of 3 cm or smaller at Taipei Veterans General Hospital between 2004 and 2012 were retrospectively reviewed. The association between clinicopathological variables and lymph node metastasis was analysed by univariate and multivariate logistic regression.
  
  
  RESULTS
  Among the 471 patients, there were 386 (82.0%) patients with pathological N0 status, 35 (7.4%) with pathological N1 status and 50 (10.6%) with pathological N2 status. Greater tumour size (P = 0.002), presence of a micropapillary pattern (P < 0.001), presence of a solid pattern (P < 0.001) and predominant pattern group (micropapillary/solid predominant) (P = 0.001) were significantly associated with higher percentage of occult N2 lymph node metastasis. In multivariate analysis, greater tumour size (P = 0.008), presence of micropapillary pattern (P < 0.001) and presence of solid pattern (P = 0.001) were significant predictors of occult N2 lymph node metastasis in tumours of 3 cm or smaller. When histological pattern was entered as the predominant pattern in multivariate analysis, micropapillary/solid predominant pattern (P = 0.005) was also a significant predictor of occult N2 lymph node metastasis.
  
  
  CONCLUSIONS
  The presence of micropapillary or solid pattern, as well as micropapillary/solid predominant pattern, is significantly associated with occult N2 lymph node metastasis in lung adenocarcinoma. Radical mediastinal lymph node dissection may help to identify occult lymph node metastasis in these patients.
authors.affiliation: Division of Thoracic Surgery, Department of Surgery, Taipei Veterans General Hospital and School of Medicine, National Yang-Ming University, Taipei, Taiwan bradley.hung@gmail.com.
authors.forename: Jung-Jyh
authors.initials: JJ
authors.lastname: Hung
authors.affiliation: Department of Pathology and Laboratory Medicine, Taipei Veterans General Hospital, Taipei, Taiwan Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Yi-Chen
authors.initials: YC
authors.lastname: Yeh
authors.affiliation: Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan Department of Internal Medicine, Chang Gung Memorial Hospital and School of Medicine, Chang Gung University, Taipei, Taiwan.
authors.forename: Wen-Juei
authors.initials: WJ
authors.lastname: Jeng
authors.affiliation: Division of Thoracic Surgery, Department of Surgery, Taipei Veterans General Hospital and School of Medicine, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Yu-Chung
authors.initials: YC
authors.lastname: Wu
authors.affiliation: Department of Pathology and Laboratory Medicine, Taipei Veterans General Hospital, Taipei, Taiwan Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Teh-Ying
authors.initials: TY
authors.lastname: Chou
authors.affiliation: Division of Thoracic Surgery, Department of Surgery, Taipei Veterans General Hospital and School of Medicine, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Wen-Hu
authors.initials: WH
authors.lastname: Hsu
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis / Q000556:secondary* / Q000601:surgery; D000077192:Adenocarcinoma of Lung; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008175:Lung Neoplasms / Q000175:diagnosis / Q000556:secondary* / Q000601:surgery; D008197:Lymph Node Excision; D008198:Lymph Nodes / Q000473:pathology; D008207:Lymphatic Metastasis; D008297:Male; D008482:Mediastinum; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D012189:Retrospective Studies; D013997:Time Factors; D014057:Tomography, X-Ray Computed
keywords: Histology; Lung adenocarcinoma; Lymph node metastasis; Prognosis; Survival