Radiosurgery for the treatment of spinal melanoma metastases

The role of stereotactic radiosurgery in treating metastatic melanoma involving the spine has previously been limited. Conventional external beam radiotherapy lacks the precision to allow delivery of large single-fraction doses of radiation and simultaneously to limit the dose delivered to radiosensitive structures such as the spinal cord. This study evaluated the clinical efficacy of radiosurgery for the treatment of melanoma spinal metastases in 28 patients.

Thirty-six melanoma spine metastases were treated with a single-session radiosurgery technique (1 cervical, 11 thoracic, 13 lumbar, and 11 sacral) with a follow-up period of 3-43 months (median 13 months). Tumor volume ranged from 4.1 to 153 cm3 (mean 47.6 cm3). Twenty-three of the 36 lesions had received prior external beam irradiation.

Maximum tumor dose was maintained at 17.5-25 Gy (mean 21.7 Gy). Spinal cord volume receiving > 8 Gy ranged from 0.0 to 0.7 cm3 (mean 0.26 cm3); spinal canal volume at the cauda equina level receiving > 8 Gy ranged from 0.0 to 3.5 cm3 (mean 0.98 cm3). No radiation-induced toxicity occurred during the follow-up period. Axial and radicular pain improved in 27 of 28 patients (96%) who were treated primarily for pain. Long-term tumor control was seen in 3 of 4 cases treated primarily for radiographic tumor progression. Two patients went on to require open surgical intervention for tumor progression resulting in neurological deficit.

Spinal radiosurgery offers a therapeutic modality for the safe delivery of large dose fractions of radiation therapy in a single fraction for the management of spinal metastases in patients with advanced melanoma that are often poorly controlled with alternative conventional external beam radiation therapy, and is successful even in patients with previously irradiated lesions.