William J. Vogel

CyberKnife Frameless Stereotactic Radiosurgery for Spinal Lesions: Clinical Experience in 125 Cases

OBJECTIVE: The role of stereotactic radiosurgery for the treatment of intracranial lesions is well established. Its use for the treatment of spinal lesions has been limited by the availability of effective targe-immobilizing devices. Conventional external beam radiotherapy lacks the precision to allow delivery of large doses of radiation near radiosensitive structures such as the spinal cord. The CyberKnife (Accuray, Inc., Sunnyvale, CA) is an image-guided frameless stereotactic radiosurgery system that allows for the radiosurgical treatment of spinal lesions. This study evaluated the feasibility and effectiveness of the treatment of spinal lesions with a single-fraction radiosurgical technique using the CyberKnife. METHODS: The CyberKnife system uses the coupling of an orthogonal pair of x-ray cameras to a dynamically manipulated robot-mounted linear accelerator with six degrees of freedom that guides the therapy beam to the intended target without the use of frame-based fixation. Real-time imaging allows the tracking of patient movement. Cervical spine lesions were located and tracked relative to cranial bony landmarks lower spinal lesions were tracked relative to fiducial bone markers. In this prospective cohort evaluation of a spine radiosurgery technique, 125 spinal lesions in 115 consecutive patients were treated with a single-fraction radiosurgery technique (45 cervical, 30 thoracic, 36 lumbar, and 14 sacral). There were 17 benign tumors and 108 metastatic lesions. All dose plans were calculated on the basis of computed tomographic images acquired from 1.25-mm slices with an inverse treatment planning technique. Radiosurgical circular cones ranging in diameter from 5 to 40 mm were used. RESULTS: Tumor volume ranged from 0l3 to 232 cm 3 (mean, 27.8 cm 3 ). Seventy-eight lesions had received external beam irradiation previously. Tumor dose was maintained at 12 to 20 Cy to the 80% isodose line (mean, 14 Gy); canal volume receiving more than 8 Gy ranged from 0.0 to 1.7 cm 3 (mean, 0.2 cm 3 ). No acute radiation toxicity or new neurological deficits occurred during the follow up period (range, 9-30 mo median, 18 mo). Axial and radicular pain improved in 74 of 79 patients who were symptomatic before treatment. CONCLUSION: This is the first large prospective evaluation of this frameless imageguided spinal radiosurgery system. The Cyberknife system was found to be feasbile, safe, and effective. The major potential benetits of radiosurgical ablation of spinal lesions are short treatment time in an outpatient setting with rapid recovery and symptomatic response. This technique offers a successial therapeutic modality for the treatment of a variety of spinal lesions as a primary treatment or for lesions not amenable to open surgical techniques, in medically inoperable patients, in lesions located in previously irradiated sites or as an adjunct to surgery.

Combination kyphoplasty and spinal radiosurgery: a new treatment paradigm for pathological fractures

OBJECT Patients with symptomatic pathological compression fractures require spinal stabilization surgery for mechanical back pain control and irradiation for the underlying malignant process. The authors evaluated a treatment paradigm of closed fracture reduction and fixation involving kyphoplasty and subsequent spinal radiosurgery. METHODS Twenty-six patients (six men and 20 women, mean age 72 years) with pathological compression fractures (16 thoracic and 10 lumbar) were prospectively evaluated. Histological diagnoses included 11 lung, nine breast, four renal, one cholangiocarcioma, and one ocular melanoma. Seven lesions had received prior external-beam radiation therapy. All patients underwent kyphoplasty that involved the percutaneous transpedicular technique. Fiducial markers allowing for image guidance during CyberKnife treatment were placed, at time of the kyphoplasty, in the pedicles at adjacent levels. Patients underwent single-fraction radiosurgery (mean time after kyphoplasty 12 days) in an outpatient setting. The tumor dose was maintained at 16 to 20 Gy (mean 18 Gy) to the 80% isodose line. The treated tumor volume ranged from 12.7 to 37.1 cm3. No acute radiation-induced toxicity or new neurological deficit occurred during the follow-up period (range 11-24 months, median 16 months). Axial pain improved in 24 (92%) of 26 patients. CONCLUSIONS The combined kyphoplasty and spinal radiosurgery treatment paradigm was found to be clinically effective in patients with pathological fractures; there was no significant spinal canal compromise. In this technique two minimally invasive surgical procedures are combined to avoid the morbidity associated with open surgery while providing both immediate fracture fixation and administering a single-fraction tumoricidal radiation dose.

Single-fraction radiosurgery for the treatment of spinal breast metastases

The spine is the most common site of bony metastases in patients with osseous breast carcinoma metastases. Spine metastases are the source of significant pain and occasionally neurologic deficit in this patient population. Conventional external beam radiotherapy lacks the precision to allow delivery of large single‐fraction doses of radiation and simultaneously limit the dose to radiosensitive structures such as the spinal cord. This study evaluated the clinical efficacy of the treatment of spinal breast carcinoma metastases with a single‐fraction radiosurgical technique.

Frameless stereotactic radiosurgery for recurrent head and neck carcinoma.

The aim of this study was to assess the feasibility and toxicity of stereotactic radiosurgery (CK-SRS) using the CyberKnife® Frameless Radiosurgery System (Accuray Inc., Sunnyvale, CA) in the management of recurrent squamous cell carcinoma of the head and neck region (SCCHN). Between November 2001 and February 2004, 22 patients with recurrent, previously irradiated SCCHN were treated with CK-SRS. The following endpoints were assessed post-CK-SRS: local control (LC), cause-specific survival (CSS), overall survival (OS), symptom relief, and acute and late toxicity. Kaplan-Meier survival analyses were used to estimate the LC, CSS, and OS rates. Clinical symptoms were graded as “improved,” “stable,” or “progressed” after CK-SRS. Acute and late toxicity were graded according to the National Cancer Institute Common Toxicity Criteria (CTC) scale, version 2.0. Seventeen patients were followed until their death. The median follow-up in the remaining five patients was 19 months (range 11–40 months). The median survival time for the entire cohort was 12 months from the time of CK-SRS. The 2-year LC, CSS, and OS rates were 26%, 26%, and 22%, respectively. After CK-SRS, symptoms were improved or stable in all but one patient who reported increasing pain. The treatment was well tolerated, with one case each of Grade 2 and 3 mucositis. There were no acute Grade 4 or 5 CTC toxicities. There were no late toxicities in this cohort. Frameless stereotactic radiosurgery for recurrent SCCHN is feasible and safe in the setting of high doses of prior irradiation. The majority of patients experienced palliation of disease without excess toxicity.

Evaluation of CyberKnife Frameless Real-Time Image-Guided Stereotactic Radiosurgery for Spinal Lesions

Background: This study evaluated the CyberKnife frameless image-guided radiosurgery system for the treatment of spinal lesions. Methods: This system utilizes the coupling of an orthogonal pair of X-ray cameras to a dynamically manipulated robot-mounted linear accelerator that guides the therapy beam to the intended target without the use of frame-based fixation. Cervical spine lesions are located and tracked relative to skull bony landmarks; lower spinal lesions are tracked relative to fiducial markers. 125 spinal lesions in 115 consecutive patients were treated with a single-fraction radiosurgery technique. Results: Tumor volume ranged from 0.3 to 232 ml (mean 27.8 ml). Tumor radiation dose was maintained at 12–20 Gy to the 80% isodose line (mean 14 Gy); the spinal cord or canal volume receiving greater than 8 Gy ranged from 0.0 to 1.7 ml (mean 0.2 ml). No acute radiation toxicity or new neurological deficits occurred during the follow-up period (3–24 months). Conclusions: The CyberKnife system was found to be feasible, safe and effective. The major potential benefits of radiosurgical ablation of spinal lesions are short treatment time in an outpatient setting with rapid recovery and good response.

CyberKnife Frameless Radiosurgery for the treatment of extracranial benign tumors.

Limited data exists for the use of radiosurgery for benign extracranial tumors. The purpose of this study was to evaluate the feasibility, toxicity, and local control of patients with benign extracranial lesions treated with the CyberKnife Frameless Radiosurgery System. From September 2001 thru January 2004, 59 benign tumors in 44 patients were treated using the CyberKnife a frameless image-guided radiosurgery system. Of these tumors, there were 21 neurofibromas, ten schwannomas, eight meningiomas, eight hemangioblastomas, seven paragangliomas, two hemangiopericytomas, one pseudotumor, one ependymoma, and one arteriovenous malformation (AVM). The anatomic locations of these tumors were spinal (25 cervical, four thoracic, 14 lumbar, and two sacral), neck (eight), orbital (three), brainstem (one), and foramen magnum (one). All patients were treated in a single fraction except three lesions were treated in a fractionated manner. The median treatment delivery time per fraction was 59 minutes (range 11–194). Twenty three lesions initially underwent surgical resection. Ten lesions received prior external beam radiation with a median dose 48 Gy (range 40–54 Gy), and one lesion received two prior CyberKnife treatments for a total dose of 32 Gy to the 80% isodose line. The median follow-up was eight months (range 1–25 months). Acute and late toxicity was graded using the National Cancer Institute Common Toxicity Criteria (CTC) scale. Symptomatic response was documented as “improved,” “stable,” or “progression”. The median tumor dose delivered was 16.0 Gy to the 80% isodose line (range 10–31 Gy). The median tumor volume was 4.3 cc (range 0.14–98.6 cc). The median spinal cord volume receiving more than 8 Gy was 0.035 cc (range 0–2.5 cc) and the median maximum spinal cord dose 11.5 Gy (range 0–19.8 Gy). There were no patients that suffered a significant (Grade 3, 4, or 5) acute toxicity. There was no observed late toxicity. 78% of patients experienced an improvement of their pre-treatment symptoms while only one patient experienced symptom progression. Of the 26 patients who underwent follow-up imaging, the local control rate was 96%. This study suggests that CyberKnife Radiosurgery is a safe and efficacious treatment modality for benign tumors, even for those patients with recurrent previously irradiated lesions.

Radiosurgery for the Management of Spinal Metastases

Background/Aims: Large clinical experience with spinal radiosurgery to properly assess clinical experience has previously been limited. This study evaluated the clinical outcomes of single fraction