Factors influencing the use of single vs multiple fractions of palliative radiotherapy for bone metastases: A 5-year review

Aims: Evidence from a number of randomised trials and meta-analyses supports the use of single-fraction radiotherapy for the palliation of painful bone metastases. This study explores patient and treatment factors that influence the choice of single compared with multiples fraction radiotherapy for the treatment of bone metastases in clinical practice. Materials and methods: The Princess Margaret Hospital Palliative Radiation Oncology Program Database served as the basis for our report. All courses of treatment delivered for bone metastases were extracted. Courses were classified into single or multiple fractions. Clinical characteristics were compared between the two groups. Results: Between 1998 and 2002, 882 courses of radiotherapy were delivered for the treatment of bone metastases, of which 283 (32%) were a single fraction. The proportion of single-fraction treatments was 37% in 1998, 30% in 1999 and 43% in 2000, but dropped to 26% and 28% in 2001 and 2002, respectively (P = 0.02). Patients treated with single fractions were significantly older (68 +/- 12 years vs 64 +/- 12 years), and had more weight loss and poor performance status. Single fractions included 20% of treatments in palliative irradiation of the spine, 36% in the pelvis and long bones, and 59% in the chest wall (P < 0.001). There was no significant difference in patients gender, primary cancers, number of metastatic sites, treating physicians, enrollment in a clinical trial and general radiotherapy waiting time in our department. Multivariate analysis indicated age (P = 0.001), performance status (P < 0.001), anatomical site (P < 0.001) and year of radiotherapy (P = 0.006) as significant. Conclusion: One-third of palliative radiotherapy courses for bone metastases in our programme were given as single fractions. Performance status, age and anatomical site were significant factors affecting single compared with multiple fractionation. The variation in the use of single fractions over time may reflect the dynamic process of interpretation and application of evidence from clinical trials to practice.