Early evaluation predicts pain relief of irradiated bone metastases: a single-center prospective study

Background: Radiation therapy is a well-recognized, effective modality used for palliative care. Most studies completed to date have endpoints of one month or greater after treatment completion. This study analyzed the response rates at different time points during the first month after treatment. Methods: From May 2010 to November 2011, 61 patients treated for 74 metastases were included in the study. The end points were defined as the completion of treatment (CT) and d8, d15 and d30 after the completion of treatment. The response rate was measured by the worst pain in the last 24 hours and the administered opioid dose. Patient assessment was performed during consultations and phone appointments. Results: The overall response rate significantly improved from the CT (38%) to d8 (53.8%), d15 (53.8%) and d30 (57.1%) (respectively p < 0.001; p < 0.001 and p = 0.001). The improvement peaked at d8. Patients responding to the treatment at d8 had a significative longer pain relapse free survival (PRFS) compared to patients not responding (3.38 weeks vs 0.3 weeks; p < 0.001). From the beginning of treatment to the CT and at d8, d15 and d30, oral morphine equivalent dose (OMED) did not significantly differ. However, the pain decrease did not result in a performance status improvement, which declined over time (p < 0.001). Conclusion: Radiation therapy is an efficient treatment method for providing pain relief. This relief peaked at d8 after treatment, and the response at d8 is predictive of the response at 4 weeks. Pain management alone is not enough to improve performance status; further studies are needed to evaluate a more global supportive care approach.