Stereotactic radiosurgery for spinal metastases from renal cell carcinoma

Object. The role of stereotactic radiosurgery in treating renal cell carcinoma (RCC) metastases to the spine has previously been limited. In this study the authors evaluated the clinical outcome in patients with spinal RCC who underwent single-fraction radiosurgery. Methods. Forty-eight patients with 60 RCC metastases to the spine (six cervical, 26 thoracic, 18 lumbar, and 10 sacral) were treated with a single-fraction radiosurgery technique and were followed for a period of 14 to 48 months (median 37 months). All patients were successfully treated in an outpatient setting. The tumor volume ranged from 5.5 to 203 CM3 (mean 61.9 cm(3)). Forty-two of the total 60 lesions had been previously treated with external-beam radiation therapy (EBRT). The maximum tumor dose was maintained at 17.5 to 25 Gy (mean 20 Gy). The volume of the spinal cord exposed to greater than 8 Gy ranged from 0.01 to 3 cm(3) (mean 0.64 CM3); the volume of the spinal canal at the cauda equina level exposed to greater than 8 Gy ranged from 0.01 to 2.2 cm(3) (mean 0.65 cm(3)). No radiation-induced toxicity occurred during the follow-up period. Axial and radicular pain improved in 34 (89%) of 38 patients who were treated primarily for pain. Tumor control was demonstrated in seven of eight patients treated primarily for radiographically documented tumor progression. In time six patients required open surgical intervention for tumor progression that had caused neurological dysfunction after radiosurgery. Conclusions. Spinal radiosurgery can be a successful therapeutic modality for the delivery of large-dose single-fraction radiation to RCC spinal metastases that are often poorly controlled with conventional EBRT modalities.