Single-Fraction Stereotactic Versus Standard Conventional Multifraction Radiation For Predominantly Non-Spine Bone Metastases:A Randomized Phase Ii Trial.

11578 Background: There lacks a consensus as to the optimal radiotherapy dose and fractionation schedule for treating bone metastases. We assessed the relative efficacy of single high-dose stereotactic radiation therapy (SBRT) versus standard multifraction radiation therapy (MFRT) for alleviation of pain in patients with mostly non-spine bone metastases. Methods: This prospective, randomized, single-institution phase II non-inferiority trial enrolled patients with radiologically confirmed painful bone metastases from September 2014 through June 2018. Patients were randomly assigned in a 1:1 ratio to receive either single-fraction SBRT (12 Gy for ≥4-cm lesions or 16 Gy for < 4-cm lesions) versus MFRT to 30 Gy in 10 fractions. Results: The primary endpoint was pain response, defined by international consensus criteria as a combination of pain score and analgesic use (daily morphine-equivalent dose [MED]). Failure of pain response was defined as worsening pain score (≥2 points on a 0-to-10 scale), an increase in morphine-equivalent opioid dose of ≥50%; re-irradiation; or pathologic fracture. Among evaluable patients who received treatment per protocol, the single-fraction SBRT group had more pain responders (CR+PR) at 2 weeks (62% vs. 36% MFRT, P= 0.01), at 1 month (62% vs 36%, P= 0.01), at 3 months (72% vs. 49% MFRT, P= 0.03), and at 9 months (77% vs. 12% MFRT, P= 0.03). No differences were found in treatment-related toxicity or quality of life scores after SBRT versus MFRT; local control rates at 1 year were higher in patients receiving single-fraction SBRT. Conclusions: Delivering high-dose single-fraction SBRT is an effective, convenient treatment option for patients with painful bone metastases. Among evaluable patients, SBRT led to higher rates of pain response (CR+PR) than did MFRT and thus should be considered for patients expected to have relatively long survival. Clinical trial information: ClinicalTrials.gov ID NCT02163226.