The most common spinal lesions are metastatic tumors, which occur in 5-10% of all patients with cancer. In the U.S., spinal metastases affect more than 100,000 individuals per year. Prostate, breast, and lung cancer account for most spinal metastases; hematopoietic (non-Hodgkin's lymphoma and multiple myeloma) and renal cancer are other common sources. Benign spinal tumors and vascular malformations are much less common than spinal metastases, with an incidence of approximately 10,000 cases per year in the U.S.
Using the CyberKnife® System to treat spine lesions:
The CyberKnife® System treats lesions anywhere in the spine with high accuracy. Metastatic disease, benign spine tumors, and vascular malformations have been treated with the CyberKnife® System at all levels of the spinal column. Recent published reports show high rates of tumor control; significant, rapid, and durable pain relief; maintenance or improvement in mental and physical quality of life; and low rates of complications, comparable to that observed for intracranial radiosurgery treatments.
Xsight™ Spine Tracking System:
Spinal treatment can be performed using fiducial markers implanted in the spine, and a few centers treat upper cervical spine lesions based on skull landmarks. The Xsight Spine Tracking System, released in the Spring of 2005, localizes the target by tracking spinal skeletal structures. This greatly increases patient comfort because an implantation procedure is not required, and allows patients to be treated sooner because they do not have to recover from the implantation procedure. Recent papers have reported treatment accuracy that rivals that attainable with fiducial tracking.
T6 Solitary Breast Metastasis
(Courtesy University of Pittsburgh Medical Center)
Axial planning image for a breast metastasis to spinal T6. Conformal dose distributions avoid the critical structures of spinal cord (outlined in green) and esophagus (outlined in red).
Dose Volume Histogram (DVH) demonstrates the high dose to the tumor and the sparing of dose to the spinal cord and esophagus.
Anterior-posterior rendering of CyberKnife® beams demonstrates the non-isocentric treatment of this patient resulting in optimal treatment to the tumor with sparing of the critical structures. Light blue lines represent beams actually delivered.
Pre-treatment T2-weighted MRI showing the impingement on the cord by the compressed T6 vertebral body with a solitary breast metastasis.
One month post-treatment T2-weighted MRI shows the benefits of spinal radiosurgery in this case with significant decompression of the spinal cord. The patient experienced significant pain relief after one month and continued to experience pain relief at four months.
References
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