Recurrent Spine Lesions:
A significant body of literature has been developed describing the effectiveness of a variety of sophisticated radiotherapy and radiosurgery approaches for vertebral (spine) metastases that have recurred after conventional radiotherapy (41,42,43,43,44,45,46). It is particularly noteworthy that recurrent renal cell carcinoma (RCC) 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).
Single or multiple CyberKnife® radiosurgical approaches to maximize tumor control and minimize the risk of spinal cord radiation injury have been developed, with one center the number of treatments according to 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 relapsed after prior conventional 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 (spinal cord injury that may result in paralysis) 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 (43-46).
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