Recurrent Spine Lesions:
A significant body of literature has been developed describing the efficacy of conventionally fractionated stereotactic radiotherapy (41), helical TomoTherapy (42), single fraction CyberKnife® radiosurgery (43, 44, 45), and hypofractionated CyberKnife® radiosurgery (46), for vertebral metastases that have recurred after conventional radiotherapy. It is particularly noteworthy that recurrent renal cell carcinoma and melanoma spine metastases, traditionally considered “radioresistant,” have demonstrated a response rate on the order of 90% to retreatment with CyberKnife® radiosurgery, with an absence of serious neurologic complications (43, 44).
A tailored single fraction or hypofractionation radiosurgery regimen, which adjusts the number of CyberKnife® radiosurgical treatments due to the risk of spinal cord radiation injury has been developed, with the number of treatments determined by an 11 point spinal cord injury risk scoring system (46). This regimen has produced durable pain relief and no neurologic complications, in a series of 107 patients, all of whom had received prior spinal radiation therapy (46).
Though spinal retreatment has also been accomplished with conventional radiation (1, 2, 3), the response rate and durability of response appears lower compared with the radiosurgical results (43, 44, 45, 46). Radiation myelopathy has also been observed in occasional patients following spinal retreatment with conventional radiotherapy technique (1,2,3), which has not been reported in the radiosurgical series (43, 44, 45, 46).
|
