Stereotactic radiosurgery for spinal neoplasms: current status and future perspective.

Stereotactic radiosurgery (SRS) is increasingly utilized for the treatment of primary and metastatic spinal tumors. SRS implies high dose per fraction radiation (typically >5 Gy per fraction) is delivered to an image-guided target in 1 to 5 fractions by using conformal radiation techniques. Its use is based on the radiobiological superiority of hypofractionated high dose radiation and precision of radiation delivery using real time image-guidance facilities. Spine SRS devices can be classified into two groups according to the type of treatment unit: Cyberknife (Accuray, Inc., Sunnyvale, CA, USA) and multileaf collimation (MLC) linear accelerator (LINAC) systems. The major indications for the use of SRS include primary and metastatic spine tumors. In spine metastasis, SRS was reported to be highly effective at decreasing pain, regardless of prior radiation, with an overall pain improvement rate of 85% and local control rate of approximately 90%. Improved local control could lead to more effective palliation and potentially longer survival. Some of benign spinal disease such as schwannoma, neurofibroma, meningioma, hemangioblastoma and vascular malformations were also treated. Complications associated with spinal SRS have been rarely reported, myelopathy risk is estimated to be 0.4% of treated patients. We believe that SRS is an established treatment for patients with spinal tumors, which is both safe and highly effective. The purpose of this review is to introduce principles of spinal SRS and summarize the literature regarding the usefulness of SRS for treatment of spinal neoplasms.