title: Clinical analysis of sixty-four patients with T1aN2M0 stage non-small cell lung cancer who had undergone resection.
abstract: The aim of this study was to evaluate the clinical features of T1aN2M0 stage non-small cell lung cancer (NSCLC).
  
  
  
  From November 2008 to May 2013, 498 patients with T1a-stage NSCLC who visited the Shanghai Cancer Center were included in the study. All patients underwent a lobectomy or segmentectomy with systematic nodal resection for primary lung cancer. Analyses of gender, smoking history, primary tumor site, tumor location, tumor size, pathological classification, cancer gene, pleural invasion, number of positive lymph nodes, skip N2, single or multiple station N2, progression-free survival (PFS), and overall survival (OS) were performed.
  
  
  
  There were significant differences in tumor size, tumor size distribution, adenocarcinoma subgroup, and number of positive lymph nodes between patients at T1aN2M0 and T1aN0M0 stages. The most common histology of the T1aN2M0 subgroup was adenocarcinoma. Epidermal growth factor receptor mutations were the most common gene mutation in T1aN2M0 stage NSCLC. There were significant differences in five-year OS and PFS rates between patients with T1aN2M0, T1aN0M0, and T1aN1M0 stages. Multivariate analyses of mediastinal lymph node metastasis showed that gender, tumor size distribution, and histology type were significant predictive factors. Multivariate analyses of OS and PFS rates in the T1aN2M0 subgroup showed that the number of positive lymph nodes was a significant predictive factor.
  
  
  
  Gender, tumor size distribution, and histology type were independent predictors of mediastinal lymph node metastasis in patients with T1a stage. The number of positive lymph nodes was significantly associated with OS and PFS rates in patients with T1aN2M0 stage NSCLC.
authors.affiliation: Department of Thoracic Surgery Fudan University Shanghai Cancer Center (FUSCC) Shanghai China; Department of Oncology Shanghai Medical College Fudan University Shanghai China.
authors.forename: Jian
authors.initials: J
authors.lastname: Xiong
authors.affiliation: Department of Thoracic Surgery Fudan University Shanghai Cancer Center (FUSCC) Shanghai China; Department of Oncology Shanghai Medical College Fudan University Shanghai China.
authors.forename: Rui
authors.initials: R
authors.lastname: Wang
authors.affiliation: Department of Thoracic Surgery Fudan University Shanghai Cancer Center (FUSCC) Shanghai China; Department of Oncology Shanghai Medical College Fudan University Shanghai China.
authors.forename: Yihua
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Department of Thoracic Surgery Fudan University Shanghai Cancer Center (FUSCC) Shanghai China; Department of Oncology Shanghai Medical College Fudan University Shanghai China.
authors.forename: Haiquan
authors.initials: H
authors.lastname: Chen
keywords: Mediastinal lymph node metastases; non‐small cell lung cancer; overall survival; progression‐free survival