Stereotactic radiosurgery for primary and metastatic sarcomas involving the spine

Abstract

The treatment for spinal sarcomas is difficult due to inadequate surgical margin and an inability to deliver high dose radiation. Advanced technology of stereotactic radiosurgery (SRS) enabled higher biological effective doses of radiation to be delivered to spinal sarcomas by hypofractionation method. The authors evaluated local control rate following SRS for primary and metastatic spinal sarcomas. Thirty-two spinal sarcomas (10 primary tumors, 22 metastatic tumors) in 27 patients were treated by SRS from November 2002 to September 2009. Patients were assessed for pain status, neurological status and radiological response by regular follow-up. Overall survival and local progression-free survival were calculated and prognostic factors were sought. Median tumor volume was 18.6 ml. Radiation doses to the tumor margins ranged from 16 to 45 Gy in one to three fractions, and the median single session equivalent dose was 21.8 Gy. Follow-up ranged from 4 to 68 months (median, 22 months). Overall median survival was 29 months and no related prognostic factors were identified. During follow-up, pain was controlled in 89.3% (25/28) lesions at 6 months, in 68.2% (15/22) at 1 year, and in 61.5% (8/13) at 2 years. Tumor volume was found to be significantly related to post-SRS pain control rate. Radiological evaluation showed that local control was maintained in 96.7% (29/30) lesions at 6 months, in 78.3% (18/23) at 1 year, and in 76.9% (10/13) at 2 years. Radiation dose and tumor volume were found to be related to radiological control at 24 months following SRS. Nine cases developed recurrence between 2 and 33 months, median local progression-free survival was 23 months. Age was found to be predictive of local progression-free survival (P = 0.009). SRS proved to be an effective modality for the local control of primary and metastatic spinal sarcomas, and age was significantly related to local recurrence.