When do you prescribe steroids prior to palliative radiotherapy of bone metastases to prevent pain flare?

The Canadian study presented at ASTRO 2015 showed a decrease in pain flare prior to single dose 8Gy RT, but steroids were given for 5 days prior to RT. We often treat less then 5 days after seeing a patient in this situation. Is this something that should be done routinely for painful mets treated with a single fraction? SBRT? What duration and dose of dexamethasone is appropriate?

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Radiation Oncology · University of Alberta Faculty of Medicine

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Thanks for the interesting question. The dexamethasone was given 8mg one hour prior to single fraction radiotherapy (RT), then 8mg po daily with breakfast for four days subsequently (not five days prior to RT). A steroid taper was not utilized. Previous studies by this trial's PI investigated both a one-time dose of 8mg on the day of RT and 8mg given orally on the day of RT and for three subsequent days; both pilot studies suggested delay in onset of pain flare rather than decrease in incidence. A longer schedule was therefore chosen for the phase III RCT. The number needed to treat to prevent pain flare based on the SC23 study's dosing is 9 (based on sensitivity analysis) or 11 (based on intention-to-treat analysis). Given that there were no significant side effects associated with this regimen of dexamethasone (baseline to day 10); it was associated with improved nausea, appetite and function as reported by patients at day 10; it is short course without a taper required; prevents pain flare in some patients; is a co-analgesic, and is cheaper than increased use of breakthrough opioids (probably with less toxicity), we recommend dexamethasone 8mg po daily x five days as standard of care when instituting single fraction RT for painful uncomplicated bone metastases. As SBRT was not investigated in this trial, I cannot comment on use of steroid premedication in that setting.