BACKGROUNDThe spine is the most common site of bony metastases in patients with osseous breast carcinoma metastases. Spine metastases are the source of significant pain and occasionally neurologic deficit in this patient population. Conventional external beam radiotherapy lacks the precision to allow delivery of large singleâfraction doses of radiation and simultaneously limit the dose to radiosensitive structures such as the spinal cord. This study evaluated the clinical efficacy of the treatment of spinal breast carcinoma metastases with a singleâfraction radiosurgical technique.METHODSIn this prospective cohort evaluation, 68 breast carcinoma metastases to the spine in 50 patients were treated with a singleâfraction radiosurgery technique with a followâup period of 6â48 months, median 16 months. The most common indication for radiosurgery treatment was pain in 57 lesions, as a primary treatment modality in 8 patients, and for radiographic tumor progression, as a postsurgical boost, and for a progressive neurologic deficit in 1 patient each.RESULTSTumor volume ranged from 0.8â197 cm3 (mean, 27.7 cm3). Maximum tumor dose was maintained at 15â22.5 Gy (mean, 19 Gy). No radiationâinduced toxicity occurred during the followâup period (6â48 mo). Longâterm axial and radicular pain improvement occurred in 55 of 57 (96%) patients who were treated primarily for pain. Longâterm radiographic tumor control was seen in all patients who underwent radiosurgery as their primary treatment modality, for radiographic tumor progression, or as a postsurgical treatment.CONCLUSIONSSpinal radiosurgery was found to be feasible, safe, and clinically effective for the treatment of spinal metastases from breast carcinoma. The results indicate the potential of radiosurgery in the treatment of patients with spinal breast metastases, especially those with solitary sites of spine involvement, to improve longâterm palliation. Cancer 2005. © 2005 American Cancer Society.