title: A population-based study of the fractionation of palliative radiotherapy for bone metastasis in Ontario.
abstract: OBJECTIVE
  To describe the use of palliative radiotherapy (PRT) for bone metastases in Ontario between 1984 and 2001 and identify factors associated with the choice of fractionation.
  
  
  METHODS
  Electronic RT records from the nine provincial RT centers in Ontario were linked to the Ontario Cancer Registry to identify all courses of PRT for bone metastases.
  
  
  RESULTS
  Between 1984 and 2001, 44,884 patients received 74,432 courses of PRT for bone metastases in Ontario. The mean number of courses per patient was 1.7, and 65% of patients received only a single course of PRT for bone metastasis. The mean number of fractions per course was 3.9. The proportion of patients treated with a single fraction increased from 27.2% in 1984-1986 to 40.3% in 1987-1992 and decreased thereafter. Single fractions were used more frequently in patients with a shorter life expectancy, in older patients, and in patients who lived further from an RT center. Single fractions were used more frequently when the prevailing waiting time for RT was longer. There were wide variations in the use of single fractions among the different RT centers (intercenter range, 11.8-62.3%). Intercenter variations persisted throughout the study period and were not explained by differences in case mix.
  
  
  CONCLUSIONS
  Despite increasing evidence of the effectiveness of single-fraction PRT for bone metastases, most patients continued to receive fractionated PRT throughout the two decades of this study. Single fractions were used more frequently when waiting times were longer. There was persistent, unexplained variation in the fractionation of PRT among different centers.
authors.affiliation: Division of Cancer Care and Epidemiology, Queen's University Cancer Research Institute, Kingston, Ontario, Canada.
authors.forename: Weidong
authors.initials: W
authors.lastname: Kong
authors.forename: Jina
authors.initials: J
authors.lastname: Zhang-Salomons
authors.forename: Timothy P
authors.initials: TP
authors.lastname: Hanna
authors.forename: William J
authors.initials: WJ
authors.lastname: Mackillop
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D000704:Analysis of Variance; D001859:Bone Neoplasms / Q000532:radiotherapy* / Q000556:secondary*; D019583:Dose Fractionation, Radiation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009864:Ontario; D010166:Palliative Care / Q000379:methods*; D012042:Registries; D012737:Sex Factors