Dexamethasone for the prophylaxis of radiation-induced pain flare after palliative radiotherapy for symptomatic bone metastases: a phase II study.

Aims: Pain flare occurs in over one-third of patients receiving palliative radiotherapy for bone metastases. A single dose of dexamethasone can decrease the incidence of pain flare during the first 2 days immediately after radiotherapy. We conducted a phase II prospective study to investigate the prophylactic role of prolonged dexamethasone.

Materials And Methods: Patients with bone metastases treated with a single 8Gy were prescribed 8mg dexamethasone just before palliative radiotherapy and for 3 consecutive days after treatment. Worst pain score and analgesic consumption data were collected at baseline and daily for 10 days after treatment. Analgesic consumption was converted into a total daily oral morphine equivalent dose in the analysis. Pain flare was defined (a priori) as a two-point increase in worst pain on an 11-point numeric rating scale compared with baseline with no decrease in analgesic intake, or a 25% increase in analgesic intake with no decrease in worst pain score. To distinguish pain flare from progressive disease, we required that the worst pain score and analgesic intake returned to baseline levels after the increase/flare.

Results: Forty-one patients were evaluable (32 men, nine women). Their median age was 67 years. The overall incidence of pain flare was 9/41 (22%) within 10 days after the completion of radiotherapy. Most (55%) of these pain flares occurred on day 5. Absence of pain flare was 34/41(83%) and 39/41 (95%) for days 1-5 and 6-10 after the completion of radiotherapy, respectively.

Conclusion: Dexamethasone is effective in the prophylaxis of radiotherapy-induced pain flare after palliative radiotherapy for bone metastases. Randomised studies are needed to confirm this finding.