Independent Validation of a Risk Stratification Model Predicting Survival in Elderly Patients Irradiated for Bone Metastases

Background/Aim: Many patients with bone metastases receive palliative radiotherapy. However, treatment personalization tools are needed, due to heterogeneous survival. The aim of this study was to analyze the validity of the prognostic survival model, originally developed by Rades et al., because international variations in clinical practice and survival outcomes may impact on the performance of predictive tools. Patients and Methods: Data from a single institution were retrospectively analyzed. The study included 305 patients managed with palliative radiotherapy for bone metastases. The Rades et al. score was assigned and the resulting 3 prognostic strata were compared. Results: The median overall survival for the 3 strata was 48, 248, and 1065 days, respectively (p<0.001). However, the original break-down (17 points versus 18-25 points versus >25 points) was not in accordance with the overlapping survival curves in some of the subgroups, leading us to propose slight adjustments. The modified model also performed satisfactorily in older patients (age & GE;80 years; median survival 26, 192 and 489 days, respectively, p<0.001). Conclusion: The original Rades et al. survival score was a valid prognostic model in our Norwegian validation database. However, inclusion of patients with 18 points into the poor prognosis group is suggested as a modification to enhance the score's performance.