title: Patterns of radiotherapy re-treatment in patients with lung cancer: a retrospective, longitudinal study.
abstract: BACKGROUND
  The optimal initial radiotherapy utilization rate for lung cancer is estimated to be 76% of all new cases. The actual re-treatment rate has not been defined. Re-treatment information can aid clinical decision making and resource planning. The aim of this study was to examine the indications for re-treatment in a population cohort and report the proportion of patients who receive more than one radiotherapy treatment for lung cancer throughout their lifetime.
  
  
  METHODS
  A retrospective longitudinal analysis of a cohort of patients with lung cancer treated with radiotherapy in the South Western Sydney Area Health Services (SWSAHS) in 1993 and 1996 was performed. The indication for and timing of all episodes of radiotherapy were recorded and analyzed using SPSS Data 3.5 software (SPSS, Inc., Chicago, IL).
  
  
  RESULTS
  Of the 527 patients diagnosed with lung cancer in the study period, 279(53%) were treated at least once with radiotherapy. Initial radiotherapy was palliative for 79%, definitive for 14%, and adjuvant for 7%. The most common sites of initial radiotherapy were chest (79%), bone (10%), and brain (9%). Of the 279 patients, 73 (27%) received treatment with a second course of radiotherapy, 19 (7%) had a third radiotherapy episode, and 6 (2%) had a fourth. One patient had five radiotherapy episodes. Overall, there were 328 radiotherapy courses delivered to the 279 patients.
  
  
  CONCLUSIONS
  The re-treatment rate for our cohort was 27%, exceeding other estimations of re-treatment. Common sites re-treated were chest and bone. Re-treatment was 17% of the initial linear accelerator treatment delivery work load for lung cancer.
authors.affiliation: Cancer Therapy Centre, Liverpool Hospital, Liverpool, Sydney, NSW 1870, Australia. vjestall@hotmail.com
authors.forename: Vanessa
authors.initials: V
authors.lastname: Estall
authors.forename: Michael B
authors.initials: MB
authors.lastname: Barton
authors.forename: Shalini K
authors.initials: SK
authors.lastname: Vinod
mesh_terms: D000230:Adenocarcinoma / Q000532:radiotherapy / Q000556:secondary; D000368:Aged; D001859:Bone Neoplasms / Q000532:radiotherapy / Q000556:secondary; D018287:Carcinoma, Large Cell / Q000532:radiotherapy / Q000556:secondary; D002289:Carcinoma, Non-Small-Cell Lung / Q000473:pathology / Q000532:radiotherapy*; D018288:Carcinoma, Small Cell / Q000473:pathology / Q000532:radiotherapy*; D002294:Carcinoma, Squamous Cell / Q000532:radiotherapy / Q000556:secondary; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008175:Lung Neoplasms / Q000473:pathology / Q000532:radiotherapy; D008297:Male; D011878:Radiotherapy / Q000706:statistics & numerical data*; D012189:Retrospective Studies; D013548:Sweden / Q000453:epidemiology