Large variation in radiation therapy fractionation for multiple myeloma in Australia.

Abstract

To evaluate the patterns of use of different radiation therapy (RT) fractionation for multiple myeloma (MM) bone disease. This is a population-based cohort of patients with MM who had RT between 2012 and 2017 as captured in the statewide Victorian Radiotherapy Minimum Data Set in Australia. Data linkage was performed to identify subsets of RT delivered within 3 months of death. RT fractionation was classified into four groups: single-fraction (SFRT), 2-5, 6-10, and>10 fractions. Changes in RT fractionation use over time were evaluated with the Cochran-Armitage test for trend. Factors associated with RT fractionation were evaluated using multivariate logistic regressions. Nine hundred and sixty-seven courses of RT were delivered in 623 patients. The proportion of SFRT, 2-5, 6-10 and>10 fractions RT was 18%, 47%, 28%, and 7%, respectively. There was an increase in the use of 2-5 fractions, from 48% in 2012 to 60% in 2017 (p-trend<.001), with corresponding decrease in the use of 6-10 fractions, from 26% in 2012 to 20% in 2017 (p-trend=.003). Nine percent (40/430) of RT courses at private institutions were SFRT, compared to 25% (135/537) in public institutions (p<.001). In multivariate analyses, treatment in private institution was the strongest predictor of multifraction RT use. SFRT use was more common closer to the end of life-18%, 14%, and 33% of RT within 2-3, 1-2,<1 month of death, respectively. There is increasing use of shorter course RT (2-5 fractions) for MM over time. SFRT use remains low, with large variation in practice.