Background: Bone metastasis is the most common cause of cancer-related pain. Radiotherapy is the gold standard palliative treatment of painful bone metastases. However, pain flare is a possible adverse reaction. Dexamethasone is an effective drug to manage the pain flare. This trial will study the dexamethasone role to prevent pain flare, to determine the optimal dose schedule and to evaluate the dexamethasone related complications

Methods: From July 2016 to June 2018, 311 eligible patients with painful bone metastases entered into this three-armed, randomized study. All patients received a single 8 Gy dose of radiotherapy. Group I did not receive dexamethasone. Group II received 8 mg dexamethasone once daily administered: the day before radiotherapy, one hour prior to radiotherapy (the same day of radiotherapy) and one day after completing radiotherapy. Group III received once daily 8 mg dexamethasone given: one hour before irradiation and for two days after completing irradiation.

Results: Of the Group I (110 patients), 45 (40.9%) patients experienced pain flare. Of the Group II (101 patients) and Group III (100 patients), 18 (17.8%) and 16 (16%) patients experienced pain flare. The difference in the incidence of pain flare between the two groups which received steroid and the group which did not receive was statistically significant (P = 0.002), but there was no difference between the two groups which received different schedule of dexamethasone. No dexamethasone related complications were reported. 

Conclusion: Dexamethasone significantly decreases the pain flare incidence after palliative bone irradiation. Dexamethasone, at three doses of 8 mg, is a well-tolerated and safe schedule. Three doses schedule of dexamethasone may be considered for patients who undergo palliative radiotherapy for painful bone metastases and have no contraindication for this treatment.

Keywords: Bone metastases, Palliative irradiation, Dexamethasone, Pain flare