Single-session and multisession CyberKnife radiosurgery for spine metastases-University of Pittsburgh and Georgetown University experience.

OBJECT: The authors compared the effectiveness of single-session (SS) and multisession (MS) stereotactic radiosurgery (SRS) for the treatment of spinal metastases.
METHODS: The authors conducted a retrospective review of the clinical outcomes of 348 lesions in 228 patients treated with the CyberKnife radiosurgery at the University of Pittsburgh Cancer Institute and Georgetown University Medical Center. One hundred ninety-five lesions were treated using an SS treatment regimen (mean 16.3 Gy), whereas 153 lesions were treated using an MS approach (mean 20.6 Gy in 3 fractions, 23.8 Gy in 4 fractions, and 24.5 Gy in 5 fractions). The primary end point was pain control. Secondary end points included neurological deficit improvement, toxicity, local tumor control, need for retreatment, and overall survival.
RESULTS: Pain control was significantly improved in the SS group (SSG) for all measured time points up to 1 year posttreatment (100% vs 88%, p = 0.003). Rates of toxicity and neurological deficit improvement were not statistically different. Local tumor control was significantly better in the MS group (MSG) up to 2 years posttreatment (96% vs 70%, p = 0.001). Similarly, the need for retreatment was significantly lower in the MSG (1% vs 13%, p < 0.001). One-year overall survival was significantly greater in the MSG than the SSG (63% vs 46%, p = 0.002).
CONCLUSIONS: Single-session and MS SRS regimens are both effective in the treatment of spinal metastases. While an SS approach provides greater early pain control and equivalent toxicity, an MS approach achieves greater tumor control and less need for retreatment in long-term survivors.