Pain flare, complexity and analgesia in bone oligometastases treated with stereotactic body radiation therapy.

The aim of our study was to assess the incidence of pain flare and the effectiveness of stereotactic body radiotherapy (SBRT) in pain management of patients with bone oligometastases. We evaluated 48 patients accounting for 54 treatments. The Edmonton Classification System for Cancer Pain (ECS-CP) was applied to identify indicators of treatment-resistant pain, in patients with active pain (NRS ≥ 2) at baseline. Statistical analysis was performed to identify predictors of pain flare and pain control. Pain flare occurred in 38% of treated patients (n = 18/48): No correlation was found between pain flare and patient- or treatment-related variables. In the subset of patients with active pain at baseline (n = 23), pain control was obtained in 62% of patients at 1 year; median time to pain progression after SBRT was 29 months (CI95% 6-52 months). Presence of ≥2ECS-CP features was correlated with earlier pain progression (4 vs. 30 months, p = 0.012). Pain flare occurred in 38% of cases irrespectively of steroid premedication and dose regimen. In patient with baseline active pain, durable pain control was obtained. Presence of ≥2 complexity indicators at the ECS-CP assessment was correlated with impaired pain control and may deserve future investigation in prospective studies.