Australian population-based study of single- versus multi-fraction palliative radiotherapy for bone metastases.

Abstract

6568 Background: Single fraction palliative radiotherapy (SFRT) has been shown to be equivalent to multi-fraction radiotherapy (MFRT) for bone metastases symptom management. Remuneration for radiotherapy (RT) in Australia are largely determined by fractions delivered. We aim to determine the use of SFRT for bone metastases in Australia. Methods: We did a population-based linkage study of multiple administrative healthcare databases in Victoria, Australia: the Victorian Radiotherapy Minimum Data Set (VRMDS), the Victorian Cancer Registry (VCR), and the Birth, Death and Marriage registry (BDM). All patients with solid tumour (excluding primary bone cancer) who received palliative radiotherapy for bone metastases between 2012 and 2017 were included. The primary outcome was use of SFRT. The Cochrane-Armitage test for trend was used to evaluate SFRT use over time. Multivariable logistic regression was used to identify factors associated with SFRT use. Results: A total of 15,668 courses of RT for bone metastases were delivered to 10,351 patients. The overall proportion of SFRT was 18% (2,746/ 15,668). There was no significant change in SFRT use over time, from 18% in 2012 to 20% in 2017 (P = 0.06). Older patients were more likely to have SFRT (mean age 69.4 vs. 68.2, P < 0.001). Patients who had lung cancer (21%) and prostate cancer (19%) were more likely to have SFRT compared to other tumour types (P < 0.001). Spine RT was associated with lower use of SFRT compared to other treatment sites (14% vs. 22%, P < 0.001). Patients from remote area were more likely to have SFRT compared to patients from major cities (22% vs. 17%, P < 0.001). Patients treated in private institutions were less likely to have SFRT compared to those treated in public institutions (10% vs. 22%, P < 0.001). In multivariate analyses, patients’ age, tumour type, area of residence, and treatment institutions were independently associated with SFRT use. Conclusions: This is the largest Australian population-based cohort treated with RT for bone metastases, with low utilisation of SFRT over time. There is large variation in SFRT use depending on patient-, tumour-, geographical and institutional factors. Further work is needed to increase uptake, and reduce unwarranted variation, in SFRT use.