IngentaConnect The CyberKnife: Potential in Patients with Cranial and Spinal Tum...

Abstract:

Stereotactic radiosurgery has emerged as an accepted treatment for many types of intracranial tumors. Based on the understanding of the limitations of prior radiosurgical systems, image-guided robotic radiosurgery was developed to overcome many of these restrictions. The CyberKnife^® is a commercially available frameless image-guided radiosurgical system that provides state-of-the-art radiosurgery for intracranial tumors, and has also revolutionized the use of radiosurgery to treat tumors in other parts of the body. This review focuses on the current use of the CyberKnife^® to treat cranial and spinal tumors.

Brain metastases have long been treated with other radiosurgical systems, but the CyberKnife^® allows patients with brain metastases to be treated multiple times as successive tumors are discovered, without the repetitive placement of a stereotactic head frame. Benign tumors such as acoustic neuromas, pituitary tumors, and meningiomas are also easily treated with the CyberKnife^®, with radiographic tumor-control rates of >90% for pituitary tumors and 95% for acoustic neuromas and meningiomas. A subset of meningiomas and pituitary tumors surround the optic nerves and are considered to be perioptic tumors. Historically, these tumors have not been treatable with radiosurgery because of the risk of visual loss. The frameless nature of the CyberKnife^® allows the radiosurgery treatment to be delivered in separate stages (typically 24 hours apart); this has been shown to significantly reduce the risk of visual loss, and thus allows effective radiosurgery treatment to be delivered. Staged radiosurgery treatment has also been used at our institution to treat acoustic neuromas, with the understanding that several stages of radiation delivery may be associated with a higher level of hearing preservation than a single-staged radiosurgery treatment. Malignant gliomas and nasopharyngeal carcinoma tumors have historically been treated with conventional radiotherapy techniques. However, we have learnt that supplementing these radiotherapy treatments with a CyberKnife^® stereotactic boost after radiotherapy can improve response rates to treatment.

Spinal radiosurgery is a novel development; prior frame-based radiosurgery devices did not allow treatment of lesions outside the brain and neck. We have observed high rates of tumor control when treating benign spinal tumors with the CyberKnife^®, and have noted excellent pain relief and tumor-control rates in patients with spinal metastases. Future CyberKnife^® stereotactic applications will focus on the continual expansion of this technology to treat tumors outside the CNS, including cancers of the lung, pancreas, liver, and prostate.

The CyberKnife®: Potential in Patients with Cranial and Spinal Tumors