Changing pattern of radiation therapy for bone metastases in an Australian population-based cohort of men with prostate cancer

Introduction: To evaluate the pattern of use of single-fraction conformal radiation therapy (SF-RT) and advanced radiation therapy techniques (ART), including stereotactic body radiation therapy (SBRT), for management of bone metastases (BM) in a population-based cohort of Australian men with prostate cancer (PCa) Patient and methods: We reviewed men with metastatic PCa who received RT for BM between 2012 and 2017 as captured in the statewide Victorian Radiotherapy Minimum Data Set (VRMDS). The primary outcomes were: proportion of RT courses using SF-RT and ART. The Cochrane-Armitage test for trend was used to evaluate the changing pattern of SF-RT and ART over time. Multivariate analyses were used to identify factors associated with the primary outcomes Results: Of the 4,324 courses of palliative RT for BM, 767 (17.7%) were SF-RT, and 615 (14.2%) were ART. There was no evidence of change in SF-RT use over time (P-trend=0.13). In multivariate analyses, increasing age at RT, site of BM (rib, shoulder, pelvis, and extremities), patients’ area of residence (regional and remote), and treatment in public and metropolitan centres were associated with increased likelihood of SF-RT use. There was marked increase in ART use from 0.2% in 2012 to 24% in 2017 (11% intensity modulated RT, 13% SBRT) (P-trend<0.001). In multivariate analyses, younger age at RT, site of BM (rib and pelvis), higher socioeconomic status, and treatment in private and metropolitan centres were associated with increased likelihood of ART use. Conclusion: SF-RT continues to be a clear minority of RT schedules employed in management of BM in PCa, and the adoption of SF-RT use should be encouraged in men with limited prognosis. There has been increasing use of ART, especially SBRT, for BM in PCa over time, and we expect this will continue to increase in the era of metastatic-directed treatment for PCa.