Purpose: To determine the incidence of pain flare following radiotherapy (RT) for painful bone metastases.
Materials and methods: Patients with bone metastases treated with RT were eligible. Worst pain scores and analgesic consumption were collected before, daily during, and for 10 days after treatment. Pain flare was defined as a 2-point increase in the worst pain score (0-10) compared to baseline with no decrease in analgesic intake, or a 25% increase in analgesic intake with no decrease in worst pain score. Pain flare was distinguished from progression of pain by requiring the worst pain score and analgesic intake return to baseline levels after the increase/flare (within the 10-day follow-up period).
Results: A total of 111 patients from three cancer centers were evaluable. There were 50 male and 61 female patients with a median age of 62 years (range, 40-89 years). The primary cancers were mainly breast, lung, and prostate. Most patients received a single 8 Gy (64%) or 20 Gy in five fractions (25%). The overall pain flare incidence was 44/111 (40%) during RT and within 10 days following the completion of RT. Patients treated with a single 8 Gy reported a pain flare incidence of 39% (27/70) and, with multiple fractions, 41% (17/41).
Conclusion: More than one third of the enrolled patients experienced a pain flare. Identifying at-risk individuals and managing potential pain flares is crucial to achieve an optimal level of care.