Dose‐escalated radiation therapy is associated with better overall survival in patients with bone metastases from solid tumors: a propensity score‐matched study

We aimed to compare the overall survival (OS) of patients with bone metastases (BM) from solid tumors after standard-dose radiotherapy ([RT]; 30 Gy administered in 10 fractions; EQD2Gy  = 32.5 Gy) and dose-escalated RT (EQD2Gy  > 32.5 Gy). We retrospectively reviewed the clinical charts of 1795 patients (median age, 62.3 years; age range, 18-96 years) with BM from solid tumors who were referred for RT to our institute between 2000 and 2013. These patients were assigned to the standard-dose (n = 1125; 63%) and dose-escalated (n = 670; 37%) RT groups. OS, estimated as the duration between the first RT session and death, served as the main outcome measure. The dose-escalated RT group had a significantly better OS than the standard-dose RT group (P = 0.000). After allowing potential confounders in multivariate analysis, the RT dose retained its independent association with OS (hazard ratio [HR], 0.837; 95% confidence interval [CI], 0.753-0.929, P = 0.001). After propensity score matching of the baseline characteristics of both groups, RT dose retained its independent association with OS (HR, 0.887; 95% CI, 0.737-0.951; P = 0.011) on multivariate analysis. Dose-escalated RT exerted more favorable effects on OS in patients with non-lung cancer, those without multiple metastases, those without symptoms, and those with favorable prognosis. Dose-escalated RT was significantly associated with better OS in patients with BM from solid malignancies, particularly among those with non-lung cancer, those without multiple metastases, those without symptoms, and those with favorable prognosis.