Assessment of image-guided CyberKnife radiosurgery for metastatic spine tumors

Spinal metastases are associated with significant symptoms. From September 2005 to September 2007, 69 consecutive patients with 127 malignant spine metastatic lesions were treated at Wanfang Hospital with CyberKnife (CK) radiosurgery. The radiosurgery dose ranged from 10 to 30 Gy (mean 15.5 Gy) prescribed to the 75-85% isodose line that encompassed at least 95% of the tumor volume. We used fiducials as tracking landmarks for CK treatment of the thoracic and lumbar spine. A torso anthropomorphic phantom and GafChromic MD-55 films were used to verify the accuracy of CK radiosurgery and 2D dose distribution, demonstrated high targeting accuracy with 2% average deviation of the measured dose from the estimated dose at the set-up center and less than 5% dose deviation in 2D isodose curve. Visual Analogue Scale and Oswestry Disability Index questionnaires were used to monitor functional outcome after radiosurgery. Local tumor control at 10 months was 96.8%. Mean pain scores decreased significantly from 65 to 30 after treatment (P = 0.001). Functional disability was significantly improved after treatment (P = 0.002). The most common treatment toxicities were nausea and fatigue. In conclusion, CK radiosurgery is a well-tolerated and effective treatment for spine tumors with good local tumor control and a favorable outcome on pain and functional improvement after treatment.