Incidence of pain flare in radiation treatment of bone metastases: A literature review

PURPOSE Pain flare is a temporary increase in pain and is a potential side effect of radiotherapy treatment. However, its incidence has been reported only in recent studies, and with great variability. A few studies have reported on the use of dexamethasone as a prophylactic agent in the prevention of pain flare. The objective of this study is to present a review of the available literature regarding the incidence of pain flare and use of dexamethasone as a preventative measure. METHODS A literature search was conducted in PubMed using subject keywords including: "radiation therapy", "stereotactic radiation therapy", "bone metastases", "pain flare", and "dexamethasone". The search was limited to English only but not restricted to any time period. Additionally, a search was also conducted in the American Society for Therapeutic Radiology and Oncology (ASTRO) 2014 book of published abstracts. Inclusion criteria were primary studies published with full text and/or abstracts only. Letters to the editor were excluded. RESULTS A total of 11 studies were selected, two of which were abstracts published by ASTRO in 2014. Seven articles investigated pain flare and/or dexamethasone use for conventional external beam radiation therapy (EBRT) while the remaining four investigated stereotactic body radiation therapy (SBRT). Pain flare incidence ranged from 2 to 44% for EBRT and 10 to 68% in SBRT. The use of dexamethasone also showed to be effective in both the prophylaxis and treatment of pain flare. CONCLUSIONS Pain flare has been established as an acute toxicity of both EBRT and SBRT, although its incidence is widely variable due to differences in data collection. The use of dexamethasone in the prophylaxis of pain flare is efficacious. Future studies are required in order to both optimize the reporting of pain and the dexamethasone regimens in the prevention of pain flare.