Remineralization in a Case of Spinal Metastasis Following Radiation Treatment with CyberKnife Stereotactic Radiosurgery

In evaluating the outcomes of stereotatic radiosurgery (SRS) in the treatment of spinal metastases, authors have looked primarily at endpoints of pain relief and tumor growth suppression. The question of structural stability has been raised, but the pattern of bone remineralization has not been investigated in detail. With traditional radiation, both tumor control and pain relief are modest, and resulting bone remineralization can reach 80% with responsive tumors. SRS offers higher rates of both tumor growth control and pain relief (88%), even for radioresistant tumors, but the protection from vertebral fracture is not improved when there is more than 40% of the vertebra involved. We report a case of a partially collapsed C2 vertebral body affected by multiple myeloma, which was surgically stabilized and treated with CyberKnife SRS. Upon a 12-month follow-up period including CT imaging, remineralization of the vertebral body was observed starting at three months post-SRS that significantly progressed during the 12-month follow-up period. Final radiographic evaluation showed almost complete restoration of the structure of the vertebral body and the associated bone densities with significantly increased stability. This pattern of remineralization is contrasted with reported results of traditional radiation therapy, and its implications for stabilization are noted. Categories: Radiation Oncology, Neurosurgery