Background
Prospective single-institution series. 149 patients with spinal metastases treated with spine SBRT at MD Anderson Cancer Center. Evaluated pain outcomes, local control, and vertebral compression fracture rates after spine SBRT. Assessed the role of pre-treatment instability and dose on outcomes. Wang XS et al, JCO 2012. PMID 22285199.
Interventions and follow up
Arm A: Spine SBRT: 27 Gy in 3 fractions (9 Gy/fraction) or 30 Gy in 5 fractions (6 Gy/fraction) to target vertebral segment
Primary endpoint: Pain response, local control, vertebral compression fracture rate
mFollow up: 15 month
Primary endpoint: Pain response, local control, vertebral compression fracture rate
mFollow up: 15 month
Results
Complete + partial pain response: 86% at 3 months
1-yr local control: 88%
Vertebral compression fracture post-SBRT: 14% — predominantly lytic lesions, ≥3 levels, and high-dose-per-fraction
Pain flare (48–72 hr post-SBRT): 23% — managed with dexamethasone
1-yr local control: 88%
Vertebral compression fracture post-SBRT: 14% — predominantly lytic lesions, ≥3 levels, and high-dose-per-fraction
Pain flare (48–72 hr post-SBRT): 23% — managed with dexamethasone
Adverse events
Main adverse events: Pain flare: 23% grade 2–3 within 48 hours (prophylactic dexamethasone now standard). Vertebral compression fracture: 14% at 1 year — significantly associated with lytic lesions, ≥3 vertebral body involvement, misalignment deformity, and baseline fracture. Esophagitis: grade ≥2 in 8%.
Conclusions
Spine SBRT (27–30 Gy in 3–5 fractions) provides excellent pain relief and local control for spinal metastases. Vertebral compression fracture is the predominant late toxicity, strongly associated with lytic lesions and high dose per fraction. SINS scoring and orthopedic consultation should precede SBRT for at-risk vertebrae.
Key Limitations
Key Limitations: Single institution, non-randomized. Selection bias toward good-PS patients. Long-term follow-up (beyond 24 months) for fracture risk not fully captured. Standardized prophylactic stabilization criteria not defined in this study.
Clinical Context
This series with RTOG 0631 established the evidence base for spine SBRT 27–30 Gy/3–5 fractions. Vertebral compression fracture risk has prompted routine use of SINS scoring before SBRT. Prophylactic vertebroplasty/kyphoplasty is recommended for SINS ≥12 (unstable) before SBRT. Dexamethasone prophylaxis for pain flare is now standard.
References