title: Predictive risk factors for lymph node metastasis in patients with small size non-small cell lung cancer.
abstract: BACKGROUND
  Accurate clinical staging of non-small cell lung cancer (NSCLC) is essential for developing an optimal treatment strategy. This study aimed to determine the predictive risk factors for lymph node metastasis, including both N1 and N2 metastases, in clinical T1aN0 NSCLC patients.
  
  
  METHODS
  We retrospectively evaluated clinical T1aN0M0 NSCLC patients who showed no radiologic evidence of lymph node metastasis, and who had undergone surgical pulmonary resection with systematic mediastinal node dissection or sampling at the First Affiliated Hospital of Zhejiang University between January 2011 and June 2013. Univariate and multivariate logistic regression analyses were performed to identify predictive factors for node metastasis.
  
  
  RESULTS
  Pathologically positive lymph nodes were found in 16.2% (51/315) of the patients. Positive N1 nodes were found in 12.4% (39/315) of the patients, and positive N2 nodes were identified in 13.0% (41/315) of the patients. Some 9.2% (29/315) of the patients had both positive N1 and N2 nodes, and 3.8% (12/315) of the patients had nodal skip metastasis. Variables of preoperative radiographic tumor size, non-upper lobe located tumors, high carcinoembryonic antigen (CEA) levels and micropapillary predominant adenocarcinoma (AC) were identified as predictors for positive N1 or N2 node multivariate analysis.
  
  
  CONCLUSIONS
  Pathologically positive lymph nodes were common in small size NSCLC patients with clinical negative lymph nodes. Therefore, preoperative staging should be performed more thoroughly to increase accuracy, especially for patients who have the larger size, non-upper lobe located, high CEA level or micropapillary predominant ACs.
authors.affiliation: Department of Thoracic Surgery, First Hospital, College of Medicine, Zhejiang University, Hangzhou 310003, China.
authors.forename: Feichao
authors.initials: F
authors.lastname: Bao
authors.affiliation: Department of Thoracic Surgery, First Hospital, College of Medicine, Zhejiang University, Hangzhou 310003, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Yuan
authors.affiliation: Department of Thoracic Surgery, First Hospital, College of Medicine, Zhejiang University, Hangzhou 310003, China.
authors.forename: Xiaoshuai
authors.initials: X
authors.lastname: Yuan
authors.affiliation: Department of Thoracic Surgery, First Hospital, College of Medicine, Zhejiang University, Hangzhou 310003, China.
authors.forename: Xiayi
authors.initials: X
authors.lastname: Lv
authors.affiliation: Department of Thoracic Surgery, First Hospital, College of Medicine, Zhejiang University, Hangzhou 310003, China.
authors.forename: Zhitian
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Department of Thoracic Surgery, First Hospital, College of Medicine, Zhejiang University, Hangzhou 310003, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Hu
keywords: Non-small cell lung cancer (NSCLC); lymph node metastasis; sublobar resections