title: Intrathoracic extensive-stage small cell lung cancer: assessment of the benefit of thoracic and brain radiotherapy using the SEER database.
abstract: BACKGROUND
  Extensive-stage small cell lung cancer (ESCLC) includes metastatic disease and locally advanced disease confined to the thorax that cannot be encompassed in a typical radiation portal. We assessed and then compared the benefits of thoracic radiotherapy (TRT) and/or brain radiotherapy (BRT) on overall survival (OS) between the intrathoracic (T-ESCLC) and metastatic (M-ESCLC) groups using the Surveillance Epidemiology and End Results database.
  
  
  METHODS
  TRT and BRT data were available for 10150 patients treated from 1988-1997. The T-ESCLC group included 1774 patients. The Kaplan-Meier method was used to estimate OS and the proportional hazards model was used to estimate OS hazard ratios for prognostic factors including age, gender, race, tumor size, T/N stage, TRT, and BRT.
  
  
  RESULTS
  The 2-year OS for T-ESCLC was 7.8 % compared to 3 % in the M-ESCLC group (p < 0.001). In the T-ESCLC group, TRT and BRT were delivered to 750 and 102 patients, respectively. The 2-year OS was 13 % in the TRT group compared to 4.1 % in the no-TRT group (p ≤ 0.001) and 22.5 % in the BRT group compared to 7 % in the no-BRT group (p < 0.001). In the M-ESCLC group, TRT and BRT were delivered to 3093 and 1887 patients, respectively. The 2-year OS was 4.4 % in the TRT group compared to 2.8 % in the no-TRT group (p < 0.001) and 4.3 % in the BRT compared to 2.6 % in the no-BRT group (p < 0.001). Age, gender, TRT and BRT were significant OS prognostic factors in both groups.
  
  
  CONCLUSIONS
  Our study suggests that T-ESCLC is a disease entity distinct from M-ESCLC. Prospective studies to determine whether TRT should be recommended for the thoracic-only subgroup are warranted.
authors.affiliation: Department of Radiation Oncology, Robert Wood Johnson Medical School, Rutgers Cancer Institue of New Jersey, 195 Little Albany Street, New Brunswick, NJ, 08903, USA. omar.mahmoud@rutgers.edu.
authors.forename: Omar
authors.initials: O
authors.lastname: Mahmoud
authors.affiliation: Biostatistics Core, University of Miami Miller School of Medicine, Miami, FL, USA.
authors.forename: Deukwoo
authors.initials: D
authors.lastname: Kwon
authors.affiliation: Department of Radiation Oncology, Baylor College of Medicine, Houston, TX, USA.
authors.forename: Brad
authors.initials: B
authors.lastname: Greenfield
authors.affiliation: Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University, Baltimore, MD, USA.
authors.forename: Jean L
authors.initials: JL
authors.lastname: Wright
authors.affiliation: Department of Radiation Oncology, University of Miami Miller School of Medicine, Miami, FL, USA.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Samuels
mesh_terms: D000368:Aged; D001932:Brain Neoplasms / Q000401:mortality / Q000532:radiotherapy / Q000556:secondary; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008175:Lung Neoplasms / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging; D010043:Outcome and Process Assessment, Health Care; D011379:Prognosis; D011446:Prospective Studies; D011878:Radiotherapy / Q000379:methods; D012189:Retrospective Studies; D018426:SEER Program / Q000706:statistics & numerical data; D055752:Small Cell Lung Carcinoma / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy; D014481:United States / Q000453:epidemiology
keywords: Brain radiotherapy; Intrathoracic extensive stage; Small cell lung cancer; Survival outcome; Thoracic radiotherapy