Comparison of whole versus partial vertebral body stereotactic body radiation therapy for spinal metastases

The purpose of this study is to evaluate the difference in clinical outcomes for patients with metastatic spine disease treated with a whole versus partial vertebral body contouring approach. A retrospective study was performed for the clinical outcomes of 154 metastatic lesions to the spine in 117 patients treated with stereotactic body radiation therapy (SBRT) using the Cyberknife(TM) Robotic Radiosurgery System. Each patient was treated with a single session of radiotherapy using either a whole (WB) or a partial vertebral body contour approach (PB). The primary endpoint was re-treatment rate and the secondary endpoints were pain status, neurologic status, toxicity, tumor control, and survival. The WB group had a lower re-treatment rate (11% (WB) vs. 18.6% (PB), p=0.285). Prior surgery status (β=1.953, OR=7.052, p<0.001) was correlated to the re-treatment rate. Trends for local tumor control were distinct for both treatment groups (X(2)=3.380, p-value=0.066). Treatment group (β=-1.1017, OR=0.362, p=0.029) was significantly correlated to the local tumor control rate. The 2-year survival was 25.7% in WB and 20.9% in PB (p=0.741). Contouring the whole vertebral body for stereotactic body radiation therapy treatment of metastatic spinal lesions shows potential benefits by reducing the risk of recurrence, improving symptomatic relief and providing improved local tumor control.