title: Definitive radiotherapy for stage I nonsmall cell lung cancer: a population-based study of survival.
abstract: BACKGROUND
  The current study characterizes the overall survival (OS) and cause-specific survival (CSS) of patients with stage I nonsmall cell lung cancer (NSCLC) who were treated with radiotherapy alone, and analyzes the variables potentially affecting survival outcomes.
  
  
  METHODS
  A total of 8524 patients with stage I NSCLC (according to the sixth edition of the American Joint Committee on Cancer staging manual) who were diagnosed between 1988 and 2008 were retrospectively analyzed using the population-based Surveillance, Epidemiology, and End Results database. Cox regression analysis was used to calculate hazard ratios (HR) from multivariate analyses.
  
  
  RESULTS
  The 1-year, 2-year, and 5-year OS rates were 62%, 37%, and 11%, respectively; the corresponding lung cancer CSS survival rates were 68%, 45%, and 20%, respectively. Approximately 77% of deaths were from lung cancer (5292 of 6891 total deaths). Cardiac (n = 477 deaths) and pulmonary (other than lung cancer deaths; n = 475 deaths) deaths accounted for 14% of deaths. From Cox proportional hazards analyses, male sex (HR, 1.2) and squamous cell carcinoma histology (HR, > 1.1) were found to be significantly (P < .0001) adverse prognostic factors for both OS and lung cancer CSS. A more recent calendar year of diagnosis was associated with significantly (P < .0001) improved OS (HR, 0.84 per decade) and lung cancer CSS. This trend was also significant (P < 0.0001) when restricting analyses to those patients with tumors measuring ≤ 5 cm (n = 5402 patients). T1 classification (vs T2 or T unknown) and smaller tumor size were found to be significantly (P < .0001) favorable factors.
  
  
  CONCLUSIONS
  From a population-based registry analysis of patients with stage I NSCLC, significant (albeit modest) improvements in survival in more recent years were appreciated, which likely reflect technologic advances in the diagnosis of, staging of, and radiotherapy for NSCLC.
authors.affiliation: Department of Radiation Oncology, University of Rochester Medical Center, Rochester, New York 14642, USA. MTMilano@yahoo.com
authors.forename: Michael T
authors.initials: MT
authors.lastname: Milano
authors.forename: Hong
authors.initials: H
authors.lastname: Zhang
authors.forename: Kenneth Y
authors.initials: KY
authors.lastname: Usuki
authors.forename: Deepinder P
authors.initials: DP
authors.lastname: Singh
authors.forename: Yuhchyau
authors.initials: Y
authors.lastname: Chen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000401:mortality / Q000473:pathology* / Q000532:radiotherapy*; D002294:Carcinoma, Squamous Cell / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000401:mortality / Q000473:pathology* / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012042:Registries; D012189:Retrospective Studies; D015996:Survival Rate