Dose-Intensified Hypofractionated Stereotactic Body Radiation Therapy for Painful Spinal Metastases: Results of a Phase 2 Study

BACKGROUND: The objective of this study was to prospectively evaluate dose-intensified hypofractionated stereotactic body radiation therapy (SBRT) in patients with painful spinal metastases in a multicenter, single-arm, phase 2 study. METHODS: Patients with 2 or fewer distinct, noncontiguous, painful, mechanically stable, unirradiated spinal metastases from a solid tumor with a Karnofsky performance status >= 60 were eligible. Patients with a long (Mizumoto score <= 4) or intermediate overall survival expectancy (Mizumoto score = 5-9) received 48.5 Gy in 10 fractions or 35 Gy in 5 fractions, respectively, with SBRT. The primary outcome was the overall (complete and partial) pain response as measured with international consensus guidelines 3 months after SBRT. RESULTS: There were 57 patients enrolled between 2012 and 2015, and 54 of these patients with 60 painful vertebral metastases were analyzed. The 3-month pain response was evaluated in 42 patients (47 lesions). An overall pain response was observed in 41 lesions (87%), and the pain response remained stable for at least 12 months. The mean maximum pain scores on a visual analogue scale significantly improved from the baseline of 6.1 (standard deviation, 2.5) to 2.0 (standard deviation, 2.3) 3 months after treatment (P < .001). The 5-level EuroQol 5-Dimension Questionnaire quality-of-life (QOL) dimensions (self-reported mobility, usual activities, and pain/discomfort) significantly improved from the baseline to 3 months after treatment. The 12-month overall survival and local control rates were 61.4% (95% confidence interval [CI], 48%-74.8%) and 85.9% (95% CI, 76.7%-95%), respectively. Grade 3 toxicity was limited to acute pain in 1 patient (2%). No patient experienced radiation-induced myelopathy. Six patients (11%) developed progressive vertebral compression fractures (VCFs), and 8 patients (15%) developed new VCFs. CONCLUSIONS: Dose-intensified SBRT achieved durable local metastasis control and resulted in pronounced and long-term pain responses and improved QOL. (C) 2018 American Cancer Society.