title: Clinical characteristics and advantages of primary peripheral micro-sized lung adenocarcinoma over small-sized lung adenocarcinoma.
abstract: OBJECTIVE
  Micro-sized lung adenocarcinoma with a tumour of 1.0 cm or less could help identify the patients who would undergo the surgery treatment with limited resection; however, its clinical characteristics and survival rates remain unclear and are to be tested further.
  
  
  METHODS
  Histology, lymphatic metastasis, surgical procedure and survival rates of 366 lung adenocarcinoma patients (from January 2007 to December 2013) with a tumour of 2.0 cm or less were analysed retrospectively. Among these patients, 175 had a primary tumour with a diameter of 1.0 cm or less and 191 had a tumour of 1.1-2.0 cm. The survival of 366 patients was evaluated by the restricted mean survival time (RMST) test, and the risk factors were assessed by multivariable analysis.
  
  
  RESULTS
  Larger lesion had a significant relation to old age, male sex, preoperatively carcinoembryonic antigen (CEA) positive, invasive adenocarcinoma (IAC) and advanced-stage disease (P < 0.0001, P = 0.001, P = 0.001, P < 0.0001 and P < 0.0001, respectively). Patients with adenocarcinoma in situ (AIS)/minimally invasive adenocarcinoma obtained a better prognosis than those with IAC (5-year overall survival rate: 98.5 vs 84.3%, P = 0.001; disease-related survival rate: 98.5 versus 85.2%, P = 0.001). The 5-year overall survival rates of patients with a tumour less than 1.0 cm in comparison with 1.1-2.0 cm were 100.0 and 88.4% (P < 0.001), whereas the 5-year lung adenocarcinoma-specific survival rates were 100.0 and 89.0% (P < 0.001), respectively. Multivariable analysis for prognosis of lung adenocarcinoma patients with a tumour 2.0 cm or less in diameter revealed that histology, lymphatic metastasis and advanced pathological stage affected the 5-year overall and disease-related survival rates unfavourably (P < 0.0001, 0.002, 0.001; and P < 0.0001, 0.005, 0.001, respectively), whereas tumour size did not have an obvious influence on survival.
  
  
  CONCLUSIONS
  Micro-sized lung adenocarcinoma (1.0 cm or less) had specific clinical characteristics and more favourable survival rates. These tumours and a subtype of AIS evaluated by computed tomography images or intraoperative frozen section may be appropriate candidates for a limited resection without mediastinal lymph node dissection.
authors.affiliation: Department of Cardio-Thoracic Surgery, Zhoushan Hospital, Zhoushan, Zhejiang Province, China Lung Cancer Research Center, Zhoushan Hospital, Zhoushan, Zhejiang Province, China Cell and Molecular Biology Laboratory, Zhoushan Hospital, Zhoushan, Zhejiang Province, China.
authors.forename: Wang-Yu
authors.initials: WY
authors.lastname: Zhu
authors.affiliation: Department of Cardio-Thoracic Surgery, Zhoushan Hospital, Zhoushan, Zhejiang Province, China.
authors.forename: Lin-Lin
authors.initials: LL
authors.lastname: Tan
authors.affiliation: Lung Cancer Research Center, Zhoushan Hospital, Zhoushan, Zhejiang Province, China.
authors.forename: Zhao-Yu
authors.initials: ZY
authors.lastname: Wang
authors.affiliation: Lung Cancer Research Center, Zhoushan Hospital, Zhoushan, Zhejiang Province, China.
authors.forename: Shan-Jun
authors.initials: SJ
authors.lastname: Wang
authors.affiliation: Lung Cancer Research Center, Zhoushan Hospital, Zhoushan, Zhejiang Province, China Cell and Molecular Biology Laboratory, Zhoushan Hospital, Zhoushan, Zhejiang Province, China.
authors.forename: Li-Yun
authors.initials: LY
authors.lastname: Xu
authors.affiliation: Department of Cardio-Thoracic Surgery, Zhoushan Hospital, Zhoushan, Zhejiang Province, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Yu
authors.affiliation: Department of Cardio-Thoracic Surgery, Zhoushan Hospital, Zhoushan, Zhejiang Province, China Lung Cancer Research Center, Zhoushan Hospital, Zhoushan, Zhejiang Province, China.
authors.forename: Zhi-Jun
authors.initials: ZJ
authors.lastname: Chen
authors.affiliation: Department of Cardio-Thoracic Surgery, Zhoushan Hospital, Zhoushan, Zhejiang Province, China Lung Cancer Research Center, Zhoushan Hospital, Zhoushan, Zhejiang Province, China zyk801801@126.con.
authors.forename: Yong-Kui
authors.initials: YK
authors.lastname: Zhang
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis / Q000453:epidemiology / Q000401:mortality / Q000503:physiopathology; D000077192:Adenocarcinoma of Lung; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000175:diagnosis / Q000453:epidemiology / Q000401:mortality / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012189:Retrospective Studies; D016019:Survival Analysis
keywords: Clinical characteristics; Lung adenocarcinoma; Micro-sized; Overall survival; Prognosis; Small sized