Effectiveness of Repeat Radiotherapy for Painful Bone Metastases in Clinical Practice: A 10 Year Historical Cohort Study.

AIMS: Repeat radiotherapy for palliation of painful bone metastases is often prescribed to non-responders or those with recurrent pain, although studies on retreatment remain scarce. We assessed the effectiveness of retreatment for painful bone metastases in terms of pain relief in everyday clinical practice and identified factors associated with response. MATERIALS AND METHODS: We carried out a single-institution 10 year retrospective cohort study among 247 patients retreated for painful bone metastases. Response was defined as a decrease in pain between 2 and 12 weeks after retreatment. The overall pain response rate was calculated in an evaluable-patients-only analysis and a worst-case analysis. Multivariate logistic regression analyses were used to identify factors associated with pain response. RESULTS: A follow-up of ≥2 weeks was available in 162 of 247 patients (65%). The overall pain response was 66% (95% confidence interval 58-73%) in an evaluable-patients-only analysis and 43% (95% confidence interval 37-50%) in a worst-case analysis. Response to first irradiation (odds ratio 2.16, P = 0.049) and use of systemic therapy (odds ratio 0.39, P = 0.037) were independently associated with the response to retreatment. The median overall survival was 7.1 months. CONCLUSION: In everyday clinical practice, retreatment for painful bone metastases leads to pain reduction in 66% of evaluable patients and 43% of patients in a worst-case analysis. Patients who responded to initial radiotherapy were more likely to respond again and those on systemic therapy were less likely to respond. Overall, repeat radiotherapy should be considered in patients with persisting bone pain.