[Pain flare following palliative external beam radiotherapy: Prospective study of 41 cases].

PURPOSE: Radiotherapy plays a major role in relieving pain caused by bone metastases; paradoxically initial flare of symptom is common. Our objectives were to assess prospectively the incidence, and to identify predictor's factors of this acute complication.

PATIENT AND METHODS: Forty-one patients treated with analgesic external beam radiotherapy were followed prospectively. Patients recorded pain severity and analgesic intake was documented. Pain flare was defined as an increase of two points in the intensity of pain on the numerical scale with no reduction in analgesic intake and/or 25% increase of the analgesic intake without decreasing pain intensity.

RESULTS: Primary cancer was the breast, lung and prostate in 49%, 29% and 22% of patients respectively. Twelve patients (29%) had a pain flare. No factor was significantly associated with the occurrence of this complication. A favorable analgesic response was observed in 27 patients. The pain flare was not related to subsequent analgesic response.

CONCLUSION: Radiotherapy is an effective treatment of pain related to bone metastasis, but with a high incidence of painful exacerbation.