CyberKnife stereotactic radiosurgical treatment of spinal tumors for pain control and quality of life

The NOMS framework: approach to the treatment of spinal metastatic tumors

BACKGROUND

Spinal metastases frequently arise in patients with cancer. Modern oncology provides numerous treatment options that include effective systemic, radiation, and surgical options. We delineate and provide the evidence for the neurologic, oncologic, mechanical, and systemic (NOMS) decision framework, which is used at Memorial Sloan-Kettering Cancer Center to determine the optimal therapy for patients with spine metastases.

METHODS

We provide a literature review of the integral publications that serve as the basis for the NOMS framework and report the results of systematic implementation of the NOMS-guided treatment.

RESULTS

The NOMS decision framework consists of the neurologic, oncologic, mechanical, and systemic considerations and incorporates the use of conventional external beam radiation, spinal stereotactic radiosurgery, and minimally invasive and open surgical interventions. Review of radiation oncology and surgical literature that examine the outcomes of treatment of spinal metastatic tumors provides support for the NOMS decision framework. Application of the NOMS paradigm integrates multimodality therapy to optimize local tumor control, pain relief, and restoration or preservation of neurologic function and minimizes morbidity in this often systemically ill patient population.

CONCLUSION

NOMS paradigm provides a decision framework that incorporates sentinel decision points in the treatment of spinal metastases. Consideration of the tumor sensitivity to radiation in conjunction with the extent of epidural extension allows determination of the optimal radiation treatment and the need for surgical decompression. Mechanical stability of the spine and the systemic disease considerations further help determine the need and the feasibility of surgical intervention.

High-dose radiotherapy using helical tomotherapy for vertebral metastasis: early clinical outcomes and cord dose specification

OBJECTIVE

For several decades, radiotherapy has been widely used to treat metastatic vertebral tumors. This study was designed to assess the feasibility and early clinical outcomes of high-dose radiotherapy to treat such tumors, using helical tomotherapy.

METHODS

Between June 2009 and December 2011, 51 sites in 36 patients were treated with high-dose radiotherapy using helical tomotherapy for vertebral metastasis. Treatment outcomes and dosimetric analyses of spinal cord were retrospectively evaluated.

RESULTS

Median follow-up was 11.5 months (range, 6-34.6) for surviving patients. The median total dose and the number of fractions in the primary helical tomotherapy arm were 2700 cGy and 3 fractions, respectively. Actuarial 6-month local control rates were 85.7%, and symptomatic vertebral compression fractures developed in five patients after a median of 4.2 (range, 2.9-5.7) months. Among 13 patients with 19 metastatic sites who showed pre-treatment impairment in neurologic function, five patients (with seven sites) in whom symptoms were mild showed improvement in neuronal function. The median pre-treatment pain visual analog scale score of 7 decreased to a median of 3 after helical tomotherapy (P < 0.001) at a median of 1 month (range, 0.5-3.2) of follow-up. No significant morbidity developed during follow-up except for one grade 3 esophagitis.

CONCLUSIONS

The use of helical tomotherapy to treat metastatic vertebral tumors appears to be both safe and reliable in terms of local tumor control and early pain relief. Local progression and the risk of compression fracture in patients with pre-existing spinal instability remain the principal factors of limiting improved clinical and functional outcomes. Optimal dose-fractionation schemes and appropriate patient selection are required to achieve better outcomes with high-dose radiotherapy using helical tomotherapy.

Beyond the conventional role of external-beam radiation therapy for skeletal metastases: new technologies and stereotactic directions

BACKGROUND

Radiation therapy is a common and effective treatment modality in the management of skeletal metastases. Recent advances in technology permitting delivery of an ablative radiation dose with an image-guided stereotactic approach improve the therapeutic threshold.

METHODS

The authors reviewed the literature on conventional external-beam radiation therapy and summarized the emerging data about image-guided stereotactic body radiation therapy (SBRT) for vertebral oligometastasis.

RESULTS

Pain control can be achieved effectively with conventional external-beam radiation therapy and may be further improved with image-guided spinal SBRT. Image-guided SBRT allows delivery of an ablative radiation dose with minimal toxicity, may potentially improve local tumor control, and may enhance clinical outcomes for histologies that are considered radioresistant. However, further understanding of long-term normal tissue toxicity is lacking.

CONCLUSIONS

Radiotherapy options are expanding for patients with skeletal metastases. Image-guided spinal SBRT can deliver a safe ablative radiation dose to improve pain control and potentially local tumor control. Randomized clinical trials are ongoing to assess clinical benefits and outcome with spinal SBRT.

Fiducial-free CyberKnife radiosurgery for residual metastatic spinal tumor after decompression and instrumentation

Stereotactic spinal radiotherapy is a promising technology for use in the multidisciplinary management of benign and malignant spinal tumors. We present two patients with residual metastatic spinal tumors and their treatment with CyberKnife (Accuray, Sunnyvale, CA, USA) after decompression and instrumentation, one of which was successful and the other not. A 73-year-old male patient was admitted with bilateral extremity weakness (Grade IV) and voiding difficulty that had developed 2 days previously. CyberKnife treatment for the residual tumor after surgery with decompression and instrumentation was attempted, but could not be performed due to imaging interference caused by the instrumentation. A second patient, a 49-year-old male, was admitted with right extremity weakness and voiding difficulty that had developed 5 months previously. In this patient, we were able to perform CyberKnife treatment on the residual tumor after decompression and instrumentation. Based on these two patients, we believe that fiducial-free CyberKnife treatment is not suitable for treatment of residual metastatic spinal tumors at the upper thoracic levels, after decompression with instrumentation. This is due to the difficulties in matching digitally reconstructed radiographs with live radiographic images, as a result of the larger inclination and smaller vertebral body surface at the upper thoracic level.

Single-session and multisession CyberKnife radiosurgery for spine metastases-University of Pittsburgh and Georgetown University experience

OBJECT

The authors compared the effectiveness of single-session (SS) and multisession (MS) stereotactic radiosurgery (SRS) for the treatment of spinal metastases.

METHODS

The authors conducted a retrospective review of the clinical outcomes of 348 lesions in 228 patients treated with the CyberKnife radiosurgery at the University of Pittsburgh Cancer Institute and Georgetown University Medical Center. One hundred ninety-five lesions were treated using an SS treatment regimen (mean 16.3 Gy), whereas 153 lesions were treated using an MS approach (mean 20.6 Gy in 3 fractions, 23.8 Gy in 4 fractions, and 24.5 Gy in 5 fractions). The primary end point was pain control. Secondary end points included neurological deficit improvement, toxicity, local tumor control, need for retreatment, and overall survival.

RESULTS

Pain control was significantly improved in the SS group (SSG) for all measured time points up to 1 year posttreatment (100% vs 88%, p = 0.003). Rates of toxicity and neurological deficit improvement were not statistically different. Local tumor control was significantly better in the MS group (MSG) up to 2 years posttreatment (96% vs 70%, p = 0.001). Similarly, the need for retreatment was significantly lower in the MSG (1% vs 13%, p < 0.001). One-year overall survival was significantly greater in the MSG than the SSG (63% vs 46%, p = 0.002).

CONCLUSIONS

Single-session and MS SRS regimens are both effective in the treatment of spinal metastases. While an SS approach provides greater early pain control and equivalent toxicity, an MS approach achieves greater tumor control and less need for retreatment in long-term survivors.

Fiducial-free CyberKnife stereotactic body radiation therapy (SBRT) for single vertebral body metastases: acceptable local control and normal tissue tolerance with 5 fraction approach

This retrospective analysis examines the local control and toxicity of five-fraction fiducial-free CyberKnife stereotactic body radiation therapy (SBRT) for single vertebral body (VB) metastases. All patients had favorable performance status (ECOG 0-1), oligometastatic disease, and no prior spine irradiation. A prescribed dose of 30-35 Gy was delivered in five fractions to the planning target volume (PTV) using the CyberKnife with X-sight spine tracking. Suggested maximum spinal cord and esophagus point doses were 30 and 40 Gy, respectively. A median 30 Gy (IQR, 30-35 Gy) dose was delivered to a median prescription isodose line of 70% (IQR, 65-77%) to 20 patients. At 34 months median follow-up (IQR, 25-40 months) for surviving patients, the 1- and 2-year Kaplan-Meier local control estimates were 80 and 73%, respectively. Two of the five local failures were infield in patients who had received irradiation to the gross tumor volume and three were paravertebral failures just outside the PTV in patients with prior corpectomy. No local failures occurred in patients who completed VB radiation alone. The 1- and 2-year Kaplan-Meier overall survival estimates were 80 and 57%, respectively. Most deaths were attributed to metastatic disease; one death was attributed to local recurrence. The mean maximum point doses were 26.4 Gy (SD, 5.1 Gy) to the spinal cord and 29.1 Gy (SD, 8.9 Gy) to the esophagus. Patients receiving maximum esophagus point doses greater than 35 Gy experienced acute dysphagia (Grade I/II). No spinal cord toxicity was documented. Five-fraction fiducial-free CyberKnife SBRT is an acceptable treatment option for newly diagnosed VB metastases with promising local control rates and minimal toxicity despite the close proximity of such tumors to the spinal cord and esophagus. A prospective study aimed at further enhancing local control by targeting the intact VB and escalating the total dose is planned.

Follow-up CT and MR findings of osteoblastic spinal metastatic lesions after stereotactic radiotherapy

PURPOSE

We retrospectively analyzed pre and post-stereotactic radiotherapy CT and MRI findings and volume changes for osteoblastic spinal metastatic lesions.

MATERIALS AND METHODS

Of 114 lesions in 72 patients, 11 were osteoblastic. CT and MR images were reviewed to determine tumor volume, CT attenuation, T2 signal intensities, and contrast enhancement.

RESULTS

Tumor volume did not change for 10 lesions and increased for 1 lesion. CT attenuation increased for 8 lesions with heterogeneous T2 signal intensities. Of these 8 lesions, 4 had patterns of dark signal foci and the other 4 had patterns of both dark and bright signal foci. T2 signal intensity became heterogenous, with dark and bright foci, for 2 of 3 lesions for which CT attenuation decreased, and normalized for the third lesion. The degree of contrast enhancement decreased for 6 lesions and did not change for 5 lesions.

CONCLUSION

There were no changes in volume except for one case. On CT images, sclerotic changes were more common than loss of sclerotic foci. On T2-weighted images, dark signal intensities with or without bright signal foci developed and the degree of enhancement decreased for more than half of the cases.

Radiosurgery for Benign Tumors of the Spine: Clinical Experience and Current Trends

In distinction to the development of the clinical indications for intracranial radiosurgery, spine radiosurgery's initial primary focus was and still remains the treatment of malignant disease. The role of stereotactic radiosurgery for the treatment of intracranial benign tumors has been well established. However, there is much less experience and much more controversy regarding the use of radiosurgery for the treatment of benign tumors of the spine. This study presents the clinical experience and current trends of radiosurgery in the treatment paradigm of benign tumors of the spine as part of a dedicated spine radiosurgery program. Forty consecutive benign spine tumors were treated using cone beam computed tomography (CBCT) image guidance technology for target localization. Lesion location included 13 cervical, 9 thoracic, 11 lumbar, and 7 sacral tumors. Thirty-four cases (85%) were intradural. The most common tumor histologies were schwannoma (15 cases), neurofibroma (7 cases), and meningioma (8 cases). Eighteen cases (45%) had previously undergone open surgical resection, and 4 lesions (10%) had previously been treated with conventional fractionated external beam irradiation techniques. This cohort was compared to a prior institutional experience of 73 consecutive benign spine tumors treated with radiosurgery. No subacute or long term spinal cord or cauda equina toxicity occurred during the follow-up period (median 26 months). Radiosurgery was used as the primary treatment modality in 22 cases (55%) and for recurrence after prior open surgical resection in 18 cases (45%). The mean prescribed dose to the gross tumor volume (GTV) was 14 Gy (range 11 to 17) delivered in a single fraction in 35 cases. In 5 cases in which the tumor was found to be intimately associated with the spinal cord with distortion of the spinal cord itself, the prescribed dose to the GTV was 18 to 21 Gy delivered in 3 fractions. The GTV ranged from 0.37 to 94.5 cm3 (mean 13.2 cm3, median 5.1 cm3). No evidence of tumor growth was seen on serial imaging in any case. Compared to the prior cohort, there was a trend towards increased patient age, GTV, and use of radiosurgery in the post-surgical setting, as well as a simultaneous decrease in the prescription dose. Radiosurgery is a safe and clinically effective treatment alternative for benign spinal neoplasms. While surgical extirpation is currently felt to be the best initial treatment option for most benign spinal tumors, spine radiosurgery has been demonstrated to have long-term clinical and radiographic benefit for the treatment of such lesions. In a similar manner in which spine radiosurgery has become a primary treatment option for a variety of intracranial benign tumors, radiosurgery may become the most favorable treatment alternative for similar histologies when found in the spine. The application of radiosurgery for non-neoplastic spine disease deserves future investigation.

Impact of immobilization on intrafraction motion for spine stereotactic body radiotherapy using cone beam computed tomography

PURPOSE

Spine stereotactic body radiotherapy (SBRT) involves tight planning margins and steep dose gradients to the surrounding organs at risk (OAR). This study aimed to assess intrafraction motion using cone beam computed tomography (CBCT) for spine SBRT patients treated using three immobilization devices.

METHODS AND MATERIALS

Setup accuracy using CBCT was retrospectively analyzed for 102 treated spinal metastases in 84 patients. Thoracic and lumbar spine patients were immobilized with either an evacuated cushion (EC, n = 24) or a semirigid vacuum body fixation (BF, n = 60). For cases treated at cervical/upper thoracic (thoracic [T]1-T3) vertebrae, a thermoplastic S-frame (SF) mask (n = 18) was used. Patient setup was corrected by using bony anatomy image registration and couch translations only (no rotation corrections) with shifts confirmed on verification CBCTs. Repeat imaging was performed mid- and post-treatment. Patient translational and rotational positioning data were recorded to calculate means, standard deviations (SD), and corresponding margins ± 2 SD for residual setup errors and intrafraction motion.

RESULTS

A total of 355 localizations, 333 verifications, and 248 mid- and 280 post-treatment CBCTs were analyzed. Residual translations and rotations after couch corrections (verification scans) were similar for all immobilization systems, with SDs of 0.6 to 0.9 mm in any direction and 0.9° to 1.6°, respectively. Margins to encompass residual setup errors after couch corrections were within 2 mm. Including intrafraction motion, as measured on post-treatment CBCTs, SDs for total setup error in the left-right, cranial-caudal, and anterior-posterior directions were 1.3, 1.2, and 1.0 mm for EC; 0.9, 0.7, and 0.9 mm for BF; and 1.3, 0.9, and 1.1 mm for SF, respectively. The calculated margins required to encompass total setup error increased to 3 mm for EC and SF and remained within 2 mm for BF.

CONCLUSION

Following image guidance, residual setup errors for spine SBRT were similar across three immobilization systems. The BF device resulted in the least amount of intrafraction motion, and based on this device, we justify a 2-mm margin for the planning OAR and target volume.

Minimal Access Spine Surgery (MASS) for Decompression and Stabilization Performed as an Out-Patient Procedure for Metastatic Spinal Tumours Followed by Spine Stereotactic Body Radiotherapy (SBRT): First Report of Technique and Preliminary Outcomes

We report a novel approach in the treatment of spinal metastases with epidural disease and mechanical instability using a combined minimal access spine surgery (MASS) technique followed by spine stereotactic body radiotherapy (SBRT). This study was performed as a retrospective review of the first ten consecutive patients treated with this combined approach. The MASS technique was based on a tubular retraction system to gain access for decompression and mechanical stabilization achieved using methyl-methacrylate (MMA) applied under direct visualization. SBRT consisted of one to five image-guided high dose per fraction treatments. Eight patients were symptomatic at baseline. Pain, disability, and quality of life (QOL) were prospectively determined using the visual analogue score (VAS), Oswestry Disability Index (ODI), and Short-Form-36 version 2, respectively. The median follow-up was 13 months (range, 3–18). MASS successfully decompressed each patient. The median blood loss was 335 ml. Following MASS, the median time to SBRT treatment planning was 6.5 days and subsequent median time to treatment was 7 days. Local control was observed in 7 of the 10 patients. Improvements in VAS, ODI and QOL were observed post-SBRT. We report preliminary efficacy for our MASS-SBRT combined approach for patients with spinal metastases, mechanical pain and epidural disease.

The role of stereotactic radiosurgery in metastasis to the spine

Objective

The incidence and prevalence of spinal metastases are increasing, and although the role of radiation therapy in the treatment of metastatic tumors of the spine has been well established, the same cannot be said about the role of stereotactic radiosurgery. Herein, the authors present a systematic review regarding the value of spinal stereotactic radiosurgery in the management of spinal metastasis.

Methods

A systematic literature search for stereotactic radiosurgery of spinal metastases was undertaken. Grades of Recommendation, Assessment, Development, and Education (GRADE) working group criteria was used to evaluate the qualities of study datasets.

Results

Thirty-one studies met the study inclusion criteria. Twenty-three studies were of low quality, and 8 were of very low quality according to the GRADE criteria. Stereotactic radiosurgery was reported to be highly effective in reducing pain, regardless of prior treatment. The overall local control rate was approximately 90%. Additional asymptomatic lesions may be treated by stereotactic radiosurgery to avoid further irradiation of neural elements and further bone-marrow suppression. Stereotactic radiosurgery may be preferred in previously irradiated patients when considering the radiation tolerance of the spinal cord. Furthermore, residual tumors after surgery can be safely treated by stereotactic radiosurgery, which decreases the likelihood of repeat surgery and accompanying surgical morbidities. Encompassing one vertebral body above and below the involved vertebrae is unnecessary. Complications associated with stereotactic radiosurgery are generally self-limited and mild.

Conclusion

In the management of spinal metastasis, stereotactic radiosurgery appears to provide high rates of tumor control, regardless of histologic diagnosis, and can be used in previously irradiated patients. However, the quality of literature available on the subject is not sufficient.

Stereotactic body radiation therapy for management of spinal metastases in patients without spinal cord compression: a phase 1-2 trial

BACKGROUND

Spinal stereotactic body radiation therapy (SBRT) is increasingly used to manage spinal metastases, yet the technique's effectiveness in controlling the symptom burden of spinal metastases has not been well described. We investigated the clinical benefit of SBRT for managing spinal metastases and reducing cancer-related symptoms.

METHODS

149 patients with mechanically stable, non-cord-compressing spinal metastases (166 lesions) were given SBRT in a phase 1-2 study. Patients received a total dose of 27-30 Gy, typically in three fractions. Symptoms were measured before SBRT and at several time points up to 6 months after treatment, by the Brief Pain Inventory (BPI) and the M D Anderson Symptom Inventory (MDASI). The primary endpoint was frequency and duration of complete pain relief. The study is completed and is registered with ClinicalTrials.gov, number NCT00508443.

FINDINGS

Median follow-up was 15·9 months (IQR 9·5-30·3). The number of patients reporting no pain from bone metastases, as measured by the BPI, increased from 39 of 149 (26%) before SBRT to 55 of 102 (54%) 6 months after SBRT (p<0·0001). BPI-reported pain reduction from baseline to 4 weeks after SBRT was clinically meaningful (mean 3·4 [SD 2·9] on the BPI pain-at-its-worst item at baseline, 2·1 [2·4] at 4 weeks; effect size 0·47, p=0·00076). These improvements were accompanied by significant reduction in opioid use during the first 6 months after SBRT (43 [28·9%] of 149 patients with strong opioid use at baseline vs 20 [20·0%] of 100 at 6 months; p=0·011). Ordinal regression modelling showed that patients reported significant pain reduction according to the MDASI during the first 6 months after SBRT (p=0·00003), and significant reductions in a composite score of the six MDASI symptom interference with daily life items (p=0·0066). Only a few instances of non-neurological grade 3 toxicities occurred: nausea (one event), vomiting (one), diarrhoea (one), fatigue (one), dysphagia (one), neck pain (one), and diaphoresis (one); pain associated with severe tongue oedema and trismus occurred twice; and non-cardiac chest pain was reported three times. No grade 4 toxicities occurred. Progression-free survival after SBRT was 80·5% (95% CI 72·9-86·1) at 1 year and 72·4% (63·1-79·7) at 2 years.

INTERPRETATION

SBRT is an effective primary or salvage treatment for mechanically stable spinal metastasis. Significant reductions in patient-reported pain and other symptoms were evident 6 months after SBRT, along with satisfactory progression-free survival and no late spinal cord toxicities.

FUNDING

National Cancer Institute of the US National Institutes of Health.

Kyphoplasty and intra-operative radiotheray, combination of kyphoplasty and intra-operative radiation for spinal metastases: technical feasibility of a novel approach

PURPOSE

To evaluate whether this new method is clinically applicable after theoretical and cadaver testing.

METHODS

The incidence of spinal metastases requiring therapy is increasing, due to enhanced life expectancy. Due to results from studies with epidural compression a combined surgical and radiation therapy is often chosen. Minimal invasive cement augmentation is an increasingly used technique, due to fast pain relief and immediate stabilisation. On the other hand, stereotactic radiosurgery is considered to provide a more durable response and better local disease control than conventional radiotherapy with the application of higher doses. Therefore the combination of cement stabilisation and simultaneous intra-operative radiation with immediate stabilisation and high-dose radiation could be an interesting therapeutic option. The results of a clinical feasibility study are presented.

RESULTS

17 patients could be treated with the new method. In two patients (10%) intra-operative radiation could not be applied. No surgical interventions for complications were required.

CONCLUSIONS

Summarizing Kypho-IORT is technically feasible with an intra-operative risk profile comparable to sole kyphoplasty and a shorter treatment time and hospitalisation for the patients compared to conventional multifraction radiation. Radiation could not be applied in 10% of cases due to technical difficulties. The results of this feasibility study permit further evaluation of this new technique by a dose escalation study which is currently in preparation.

Radiosurgery for metastatic spinal tumors: follow-up MR findings

BACKGROUND AND PURPOSE

MR imaging is the primary tool for evaluation and monitoring of spinal tumors. We retrospectively analyzed the MR imaging findings before and after SRS for metastatic spinal tumors.

MATERIALS AND METHODS

We reviewed MR imaging findings on 79 metastatic spinal tumor lesions in 44 patients (29 male and 15 female)who had undergone radiosurgery between November 2003 and April 2008. Posttreatment MR imaging was evaluated retrospectively for 3 aspects: 1) changes in tumor volume; 2) changes in T2 signal intensity;and 3) changes in contrast enhancement patterns.

RESULTS

With regard to tumor volume on MR images, 32 lesions(40.5%) decreased in volume (group 1), 39 (49.4%) showed no change (group 2), and 8 (10.1%) increased in volume (group 3). T2 signal intensities were unchanged in 4 lesions (type 1), homogeneously increased in 3 (type 2), and changed to a homogeneously dark signal in 4 (type 4). The T2 signal intensity was increased and inter mixed with dark signal intensity (type 3) in 68 lesions. A decrease in contrast enhancement with or without non-enhancing foci was seen in 73 lesions. A persistent homogeneous enhancement pattern was seen in all 4 of the type 1 lesions, in 1 of the 3 type 2 lesions, and in 1 of the 68 type 3 lesions.

CONCLUSIONS

Main MR imaging features of locally controlled metastatic spinal tumors included no increase in tumor volume, increased T2 signal intensity with intermixed T2 dark signal intensity,and decreased contrast enhancement. Follow-up MR imaging also provided several patterns of tumor recurrence [corrected].

Clinical application of CyberKnife for high-risk central nervous system tumors: A clinical trial report of 60 cases

The objective of the present study was to evaluate the application potential of CyberKnife for high-risk tumors of the central nervous system and to analyze the effectiveness of CyberKnife in relation to dose recovery and gain division (times). A total of Eighty-one targeted areas from 139 central nervous tumor lesions in 60 patients were treated with I-VI ranged CyberKnife for 1 week. Following CyberKnife treatment, imaging tests revealed a decrease in tumor volume, reduction of central nervous system symptoms and an increase in the life quality of patients. The advantages of CyberKnife include non-invasiveness, individualized treatment, flexibility, high accuracy and rapid treatment. CyberKnife produces slight damage and a favorable therapeutic effect and expands our concepts concerning precise radiotherapy for tumors. It is an indispensable method for personalized tumor treatment.

Metastatic spine disease in the elderly: diagnostic and management considerations

Metastatic spine disease is becoming a more frequent problem in cancer patients as advancements in treatment for primary tumors prolong patient survival. Elderly patients over 60 years of age make up the majority of these cases, with the incidence of metastatic disease several folds higher in the elderly than in any other age group. These patients are also the most challenging group to treat, given higher rates of comorbidities and decreased tolerance to medical, surgical and radiation therapies. Advancements in therapeutic strategies, including minimally invasive surgeries and stereotactic radiosurgery, have provided increasingly attractive treatment options for elderly patients owing to their decreased procedure-associated morbidity. This article will discuss efficacy and limitations of conventional, as well as more recent, treatment modalities with an emphasis on their role in the management of elderly patients.

Stereotactic body radiosurgery for spinal metastatic disease: an evidence-based review

Spinal metastasis is a problem that afflicts many cancer patients. Traditionally, conventional fractionated radiation therapy and/or surgery have been the most common approaches for managing such patients. Through technical advances in radiotherapy, high dose radiation with extremely steep drop off can now be delivered to a limited target volume along the spine under image-guidance with very high precision. This procedure, known as stereotactic body radiosurgery, provides a technique to rapidly treat selected spinal metastasis patients with single- or limited-fraction treatments that have similar to superior efficacies compared with more established approaches. This review describes current treatment systems in use to deliver stereotactic body radiosurgery as well as results of some of the larger case series from a number of institutions that report outcomes of patients treated for spinal metastatic disease. These series include nearly 1400 patients and report a cumulative local control rate of 90% with myelopathy risk that is significantly less than 1%. Based on this comprehensive review of the literature, we believe that stereotactic body radiosurgery is an established treatment modality for patients with spinal metastatic disease that is both safe and highly effective.

Safety and feasibility of image-guided robotic radiosurgery for patients with limited bone metastases of prostate cancer

OBJECTIVE

To determine the safety and feasibility after image-guided single fraction robotic stereotactic radiosurgery (SRS) in patients with bone metastases of prostate cancer.

MATERIALS AND METHODS

Forty patients with 64 bone metastases of prostate cancer were prospectively enrolled in a single center study and underwent 54 consecutive outpatient single session SRS procedures during a 4-year period. F-18 choline PET/CT in addition to standard CT imaging was done prior to SRS in all patients. Nineteen patients were under anti-androgen therapy, 8 patients had undergone chemotherapy before SRS. Overall survival and freedom from local tumor recurrence was analyzed with the Kaplan-Meier method.

RESULTS

Mean follow-up was 14 months (3-48 months). Seventy-five percent of patients had a single bone metastasis. The median tumor volume was 13 cc. The mean prescribed tumor dose was 20.2 Gy (16.5-22 Gy). Eight patients had died at the time point of the data analysis. The actuarial 6-months, 12-months, and 24-months local tumor control rate was 95.5% (95% CI: 83.0-98.8) as measured by MRI and PET CT imaging. The median initial PSA before SRS was 5.4 ng/dl (CI: 1.4-8.2) and dropped to 2.7 ng/dl (CI: 0.14-10) after 3 months. One case of progressive neurological deficits was documented.

CONCLUSIONS

This first report on single session, image-guided robotic SRS documents a safe, feasible, and patient-friendly treatment option in selected patients with bone metastases of prostate cancer.

A survey of stereotactic body radiotherapy use in the United States

BACKGROUND

Stereotactic body radiotherapy (SBRT) is a technique used to deliver high, ablative doses of radiation in a limited number of fractions to ≥ 1 extracranial target(s). To the authors' knowledge, the prevalence of SBRT use among radiation oncologists in the United States is unknown.

METHODS

A random sample of 1600 American radiation oncologists was surveyed via e-mail and facsimile (fax) regarding SBRT usage, including year of adoption, motivations, disease sites treated, and common prescriptions used.

RESULTS

Of 1373 contactable physicians, 551 responses (40.1%) were received. The percentage of physicians using SBRT was 63.9% (95% confidence interval, 60%-68%), of whom nearly half adopted it in 2008 or later. The most commonly cited reasons for adopting SBRT were to allow the delivery of higher than conventional radiation doses (90.3%) and to allow retreatment (73.9%) in select patients. Academic physicians were more likely to report research as a motivation for SBRT adoption, whereas physicians in private practice were more likely to list competitive reasons. Among SBRT users, the most common disease sites treated were lung (89.3%), spine (67.5%), and liver (54.5%) tumors. Overall, 76.0% of current SBRT users planned to increase their use, whereas 66.5% of nonusers planned to adopt the technology in the future.

CONCLUSIONS

SBRT has rapidly become a widely adopted treatment approach among American radiation oncologists. Further research and prospective trials are necessary to assess the benefits and risks of this novel technology.

Simultaneous anti-angiogenic therapy and single-fraction radiosurgery in clinically relevant metastases from renal cell carcinoma

OBJECTIVE

• To analyse the safety and efficacy of simultaneous standard anti-angiogenic therapy and stereotactic radiosurgery (SRS) in patients with spinal and cerebral metastases from renal cell carcinoma.

PATIENTS AND METHODS

• In all, 106 patients with spinal (n= 55) or cerebral (n= 51) metastatic lesions and an Eastern Cooperative Oncology Group status of 0 or 1 were treated with sorafenib or sunitinib and simultaneous SRS. • The primary endpoint was local control. • Secondary endpoints were toxicity and overall survival.

RESULTS

• Median follow up was 14.7 months (range 1-42 months). Forty-five patients were treated with sunitinb and 61 patients with sorafenib. Two patients had asymptomatic tumour haemorrhage after SRS. • No skin toxicity, neurotoxicity or myelopathy occurred after SRS, and SRS did not alter the adverse effects of anti-angiogenic therapy. • Local tumour control 15 months after SRS was 98% (95% confidence interval 89-99%). The median pain score before SRS was 5 (range 1-8) and was lowered to 0 (range 0-2, P < 0.01) after SRS. There were no treatment-related deaths or late complications after SRS. • Overall survival was 17.4 months in patients with spinal lesions and 11.1 month in patients with cerebral lesions (P= 0.038).

CONCLUSIONS

• Simultaneous systemic anti-angiogenic therapy and SRS for selected patients with renal cell carcinoma who have spinal and cerebral metastases is safe and effective. • Single-fraction delivery allows for efficacious integration of focal radiation treatment into oncological treatment concepts without additional toxicity. • Further studies are needed to determine the limits of SRS for renal cell carcinoma metastases outside the brain and spine.

Technique for stereotactic body radiotherapy for spinal metastases

Stereotactic body radiotherapy (SBRT) is an emerging technique for spinal tumours that is a natural succession to brain radiosurgery. The spine is an ideal site for SBRT due to its relative immobility and the potential clinical benefits of high dose delivery, particularly to optimise local control and avoid disease progression that can result in spinal cord compression. However, the proximity of the tumour to the spinal cord, with the potential for radiation myelopathy if the dose is delivered inaccurately or if the spinal cord dose limit is set too high, demands technical accuracy with radiation myelopathy a feared complication. Spine SBRT has been delivered with either a robotic-based linac system such as the Cyberknife, or with linac-based systems equipped with a multileaf collimator and image guidance system. Regardless of the technology, spine SBRT demands sophisticated treatment planning and delivery. This case-based technical review outlines the SBRT apparatus, planning and treatment delivery in use at the University of Toronto, Toronto, Canada.

CyberKnife for hilar lung tumors: report of clinical response and toxicity

Objective

To report clinical efficacy and toxicity of fractionated CyberKnife radiosurgery for the treatment of hilar lung tumors.

Methods

Patients presenting with primary and metastatic hilar lung tumors, treated using the CyberKnife system with Synchrony fiducial tracking technology, were retrospectively reviewed. Hilar location was defined as abutting or invading a mainstem bronchus. Fiducial markers were implanted by conventional bronchoscopy within or adjacent to tumors to serve as targeting references. A prescribed dose of 30 to 40 Gy to the gross tumor volume (GTV) was delivered in 5 fractions. Clinical examination and PET/CT imaging were performed at 3 to 6-month follow-up intervals.

Results

Twenty patients were accrued over a 4 year period. Three had primary hilar lung tumors and 17 had hilar lung metastases. The median GTV was 73 cc (range 23-324 cc). The median dose to the GTV was 35 Gy (range, 30 - 40 Gy), delivered in 5 fractions over 5 to 8 days (median, 6 days). The resulting mean maximum point doses delivered to the esophagus and mainstem bronchus were 25 Gy (range, 11 - 39 Gy) and 42 Gy (range, 30 - 49 Gy), respectively. Of the 17 evaluable patients with 3 - 6 month follow-up, 4 patients had a partial response and 13 patients had stable disease. AAT t a median follow-up of 10 months, the 1-year Kaplan-Meier local control and overall survival estimates were 63% and 54%, respectively. Toxicities included one patient experiencing grade II radiation esophagitis and one patient experiencing grade III radiation pneumonitis. One patient with gross endobronchial tumor within the mainstem bronchus developed a bronchial fistula and died after receiving a maximum bronchus dose of 49 Gy.

Conclusion

CyberKnife radiosurgery is an effective palliative treatment option for hilar lung tumors, but local control is poor at one year. Maximum point doses to critical structures may be used as a guide for limiting toxicities. Preliminary results suggest that dose escalation alone is unlikely to enhance the therapeutic ratio of hilar lung tumors and novel approaches, such as further defining the patient population or employing the use of radiation sensitizers, should be investigated.

The surgical management of metastatic epidural compression of the spinal cord

Metastatic epidural compression of the spinal cord is a significant source of morbidity in patients with systemic cancer. With improved oncological treatment, survival in these patients is improving and metastatic cord compression is encountered increasingly often. The treatment is mostly palliative. Surgical management involves early circumferential decompression of the cord with concomitant stabilisation of the spine. Patients with radiosensitive tumours without cord compression benefit from radiotherapy. Spinal stereotactic radiosurgery and minimally invasive techniques, such as vertebroplasty and kyphoplasty, with or without radiofrequency ablation, are promising options for treatment and are beginning to be used in selected patients with spinal metastases. In this paper we review the surgical management of patients with metastatic epidural spinal cord compression.

Diagnosis and management of metastatic spine disease. A review

With continued growth of the elderly population and improvements in cancer therapies, the number of patients with symptomatic spinal metastases is likely to increase, and this is a condition that commonly leads to debilitating neurological dysfunction and pain. Advancements in surgical techniques of resection and spinal reconstruction, improvements in clinical outcomes following various treatment modalities, generally increased overall survival in patients with metastatic spine disease, and a recent randomized trial by Patchell and colleagues demonstrating the superiority of a combined surgical/radiotherapeutic approach over a radiotherapy-only strategy have led many to suggest increasingly aggressive interventions for patients with such lesions. Optimal management of spinal metastases encompasses numerous medical specialties, including neurosurgery, orthopedic surgery, medical and radiation oncology, radiology, and rehabilitation medicine. In this review, the clinical presentation, diagnosis, and management of spinal metastatic disease are discussed. Ultimately, the goal of treatment in patients with spinal metastases remains palliative, and clinical judgment is required to select the appropriate patients for surgical intervention.

Cyberknife: A double edged sword?

The Cyberknife represents a new, frameless stereotactic radiosurgery system which efficiently incorporates advance robotics with computerized image reconstruction to allow highly conformal image guided radiation delivery. This review focus is on the pros and cons of this new radiotherapy tool, its current indications, safety profile and future directions. A literature search of Medline, Pubmed, Biomed, Medscape and Cancer lit database were referred to retrieve relevant data/information. The authors conclude that the use of this system offers an invaluable solution to the treatment of selective tumours/lesions located close to critical structures, salvage of recurrent and metastatic lesions and potential of treatment of selective early stage malignancies like the carcinoma prostate and lung. However, it is still too premature, with insufficient follow up data to advocate it as the treatment of choice in any set up. There are several radiobiological issues that also remain in the greyzone.

Radiotherapy and radiosurgery for metastatic spine disease: what are the options, indications, and outcomes?

STUDY DESIGN

Systematic literature review.

OBJECTIVE

To determine the options, indications, and outcomes for conventional radiotherapy and radiosurgery for metastatic spine disease.

METHODS

Three research questions were determined through a consensus among a multidisciplinary panel of spine oncology experts. A systematic review of the literature was conducted regarding radiotherapy and radiosurgery for metastatic spine disease using PubMed, Embase, the Cochrane Evidence Based Medicine Database, and a review of bibliographies of reviewed articles.

RESEARCH QUESTIONS

1. What are the clinical outcomes of the current indications for conventional radiotherapy alone and stereotactic radiosurgery for metastatic spine disease? 2. What are the current dose recommendations and fractionation schedules for conventional spine radiotherapy and stereotactic radiosurgery for metastatic spine disease? 3. What are the current known patterns of failure and complications after conventional spine radiation and stereotactic radiosurgery for metastatic spine disease?

RESULTS

For conventional radiotherapy, the initial literature search yielded a total of 531 potentially relevant abstracts. Each of these abstracts was reviewed for relevance, and 62 were selected for in-depth review. Forty-nine studies met all the inclusion criteria. References from the articles included in the analysis and review articles were also examined for potential inclusion in the study. For conventional radiotherapy, 3 randomized trials (high-quality evidence), 4 prospective studies (moderate-quality evidence), and over 40 nonprospective data sets (low- or very-low-quality evidence) that included over 5000 patients in the literature were included in this review. Drawing from the same databases, a systematic search for radiosurgery yielded 195 abstracts, of which 29 met all inclusion criteria. They all represented single-institution reports (low- or very-low-quality data). No randomized data are available for spine radiosurgery.

CONCLUSION

A systematic review of the available evidence suggests that conventional radiotherapy is safe and effective with good symptomatic response and local control, particularly for radiosensitive histologies. A strong recommendation can be made with moderate quality evidence that conventional fractionated radiotherapy is an appropriate initial therapy option for patients with spine metastases in cases in which no relative contraindication exists. A systematic review of the available evidence suggests that radiosurgery is safe and provides an incremental benefit over conventional radiotherapy with more durable symptomatic response and local control independent of histology, even in the setting of prior fractionated radiotherapy. A strong recommendation can be made with low-quality evidence that radiosurgery should be considered over conventional fractionated radiotherapy for the treatment of solid tumor spine metastases in the setting of oligometastatic disease and/or radioresistant histology.

Surgical management of prostate cancer metastatic to the spine

Object

Significant improvements in neurological function and pain relief are the benefits of aggressive surgical management of spinal metastatic disease. However, there is limited literature regarding the management of tumors with specific histological features. In this study, a series of patients undergoing spinal surgery for metastatic prostate cancer were reviewed to identify predictors of survival and functional outcome.

Methods

The authors retrospectively reviewed the records of all patients who were treated with surgery for prostate cancer metastases to the spine between 1993 and 2005 at a single institution. Particular attention was given to initial presentation, operative management, clinical and neurological outcomes, and factors associated with complications and overall survival.

Results

Forty-four patients underwent a total of 47 procedures. The median age at spinal metastasis was 66 years (range 50–84 years). Twenty-four patients had received previous external-beam radiation to the site of spinal involvement, with a median dose of 70 Gy (range 30–74 Gy). Frankel scores on discharge were significantly improved when compared with preoperative scores (p = 0.001). Preoperatively, 32 patients (73%) were walking and 33 (75%) were continent. On discharge, 36 (86%) of 42 patients were walking, and 37 (88%) of 42 were continent. Preoperatively, 40 patients (91%) were taking narcotics, with a median morphine equivalent dose of 21.5 mg/day, and 28 patients (64%) were taking steroids, with a median dose of 16 mg/day. At discharge, the median postoperative morphine equivalent dose was 12 mg/day, and the median steroid dose was 0 mg/day (p < 0.001). Complications occurred in 15 (32%) of 47 procedures, with 9 (19%) considered major, and there were 4 deaths within 30 days of surgery. The median overall survival was 5.4 months. Gleason score (p = 0.002), total number of metastases (p = 0.001), and the degree of spinal canal compression (p = 0.001) were independent predictors of survival. Age ≥ 65 years at the time of surgery was an independent predictor of a postoperative complication (p = 0.005).

Conclusions

In selected patients with prostate cancer metastases to the spine, aggressive surgical decompression and spinal reconstruction is a useful treatment option. The results show that on average, neurological outcome is improved and use of analgesics is reduced. Gleason score, metastatic burden, and degree of spinal canal compression may be associated with survival following surgery, and thus should be considered carefully prior to opting for surgical management.

Treatment of spinal tumors using cyberknife fractionated stereotactic radiosurgery: pain and quality-of-life assessment after treatment in 200 patients

OBJECTIVE

Benign and malignant tumors of the spine significantly impair the function and quality of life of many patients. Standard treatment options, including conventional radiotherapy and surgery, are often limited by anatomic constraints and previous treatment. Image-guided stereotactic radiosurgery using the CyberKnife system (Accuray, Inc., Sunnyvale, CA) is a novel approach in the multidisciplinary management of spinal tumors. The aim of this study was to evaluate the effects of CyberKnife stereotactic radiosurgery on pain and quality-of-life outcomes of patients with spinal tumors.

METHODS

We conducted a prospective study of 200 patients with benign or malignant spinal tumors treated at Georgetown University Hospital between March 2002 and September 2006. Patients were treated by means of multisession stereotactic radiosurgery using the CyberKnife as initial treatment, postoperative treatment, or retreatment. Pain scores were assessed by the Visual Analog Scale, quality of life was assessed by the SF-12 survey, and neurological examinations were conducted after treatment.

RESULTS

Mean pain scores decreased significantly from 40.1 to 28.6 after treatment (P < 0.001) and continued to decrease over the entire 4-year follow-up period (P < 0.05). SF-12 Physical Component scores demonstrated no significant change throughout the follow-up period. Mental Component scores were significantly higher after treatment (P < 0.01), representing a quality-of-life improvement. Early side effects of radiosurgery were mild and self-limited, and no late radiation toxicity was observed.

CONCLUSION

CyberKnife stereotactic radiosurgery is a safe and effective modality in the treatment of patients with spinal tumors. CyberKnife offers durable pain relief and maintenance of quality of life with a very favorable side effect profile.

Cost-utility analysis of the cyberknife system for metastatic spinal tumors

OBJECTIVE

Using decision analysis, a cost-utility study evaluated the cost-effectiveness of CyberKnife (Accuray, Inc., Sunnyvale, CA) stereotactic radiosurgery (SRS) in comparison to external beam radiation therapy in the treatment of metastatic spinal malignancies.

METHODS

The published literature provided evidence on the effectiveness of the comparator interventions in the absence of primary outcomes data. Costs of care were derived from Centers for Medicare and Medicaid Services fee schedules. A Markov model was constructed from the payer perspective to simulate the outcomes of patients undergoing nonchemotherapeutic interventions for metastatic spinal tumors. Because cancer therapies bear significant health and economic consequences, the impact of treatment-related toxicities was integrated into the model. Given the terminal nature of these conditions and the limited life expectancy of the patient population, the time horizon for the analysis was limited to 12 months.

RESULTS

Patients treated with CyberKnife SRS gained an additional net health benefit of 0.08 quality-adjusted life year; the calculated cost of CyberKnife SRS was $1933 less than external beam radiation therapy for comparable effectiveness. The incremental cost per benefit for this strategy ($41 500 per quality-adjusted life year) met payers' willingness-to-pay criteria.

CONCLUSION

Cost-utility analysis demonstrated that CyberKnife SRS was a superior, cost-effective primary intervention for patients with metastatic spinal tumors compared with conventional external beam radiation therapy.

Treatment of chordomas with CyberKnife: georgetown university experience and treatment recommendations

OBJECTIVE

To determine the efficacy and safety of chordoma treatment with CyberKnife (Accuray, Inc., Sunnyvale, CA) stereotactic radiosurgery (CK/SRS).

METHODS

Eighteen patients with chordoma were treated with CK/SRS as a primary adjuvant (17 patients) or the only treatment (1 patient). The series included 24 lesions (28 treatments). The median age of the patients was 60 years (range, 24-85 years). Forty-four percent of the tumors were located in the mobile spine, 39% inside the cranium, and 17% in the sacral region. The male-to-female ratio was 1:1. The mean tumor volume was 128.0 mL (range, 12.0-457.3 mL), and the median dose of 35 Gy (range, 24.0-40.0 Gy) was delivered in 5 sessions. The median follow-up period was 46 months (range, 7-65 months).

RESULTS

There were 3 significant complications in patients with previous irradiation, including infection in the surgical/radiation site (2 patients) and decreased vision (1 patient). Improvement in pain and quality of life did not reach statistical significance (alpha = 0.05). Seven patients experienced recurrence at a median of 10 months (range, 5-38 months), and 4 patients with disseminated disease died 7 to 48 months after therapy. Two patients had a partial response, whereas 9 others had stable disease. The local control rate at 65 months was 59.1%, with an overall survival of 74.3% and disease-specific survival of 88.9%. We estimated an alpha/beta ratio of 2.45 for chordomas, which supports hypofractionation.

CONCLUSION

The CK/SRS safety and efficacy profile compares favorably with those of other treatment delivery systems. CK/SRS appears to reduce tumor volume, given an adequate dose. The authors recommend treatment with 40 Gy in 5 sessions to the clinical treatment volume, which includes the gross tumor volume and at least a 1-cm margin.

Radiosurgery for spinal malignant tumors

BACKGROUND

Radiosurgery is a special treatment method that employs highly focused radiation to destroy tumors with high precision in a single session. A broad base of scientific evidence already exists for the radiosurgical treatment of brain metastases. Recent advances in medical technology now allow radiosurgery to be extended to the spine as well.

METHODS

Selective literature review based on a PubMed search using the search terms stereotaxis, radiosurgery, stereotactic radiotherapy, accuracy, quality assurance, spine, spine metastasis, pain, Novalis, CyberKnife, Synergy, and robotics. We also present and analyze our own data as an illustration of the application of spinal radiosurgery.

RESULTS

The literature search identified 20 scientific original publications and one recent review. The data indicate that, within the specific constraints of the method, radiosurgery can arrest the growth of up to 96% of spinal metastases. Durable pain relief can be achieved in patients with tumor-associated pain syndromes. The morbidity of spinal radiosurgery is low, with a less than 1% risk of myelopathy.

CONCLUSIONS

Spinal radiosurgery is an independent, essentially noninvasive method of treatment. Different types of radiosurgical treatment apparatus are available. For properly selected patients, radiosurgery offers a good chance of therapeutic success with relatively rare complications.

FORAMINAL NERVE SHEATH TUMORS

OBJECTIVE

To conduct a retrospective review of outcomes in 15 patients with 18 foraminal tumors, including 17 benign peripheral nerve sheath tumors and 1 malignant peripheral nerve sheath tumor, who underwent CyberKnife (Accuray, Inc., Sunnyvale, CA) radiosurgery at Stanford University Medical Center from 1999 to 2006.

METHODS

Symptoms and findings, neurofibromatosis (NF) association, previous radiation, imaging, dosimetry, tumor volume, central necrosis, and the relation of these factors to outcomes were evaluated.

RESULTS

Before treatment, 1 asymptomatic patient had radiculopathic findings, 3 patients experienced local pain with intact neurological examinations, and 7 patients had radiculopathic complaints with intact (1 patient), radiculopathic (4 patients), or radiculomyelopathic examinations (2 patients). Five patients had myelopathic complaints and findings. Three patients had NF1-associated neurofibromas, 1 patient with NF2 had a schwannoma, and 1 patient had a schwannomatosis-related lesion. Two likely radiation-induced lesions, a neurofibroma and a malignant peripheral nerve sheath tumor, were observed. Prescribed doses ranging from 16 to 24 Gy, delivered in 1 to 3 fractions of 6 to 20 Gy, resulted in maximum tumor doses ranging from 20.9 to 30 Gy. Target volumes ranged from 1.36 to 16.9 mL. After radiosurgery, the asymptomatic case remained asymptomatic, and neurological findings improved. Thirteen of 15 symptomatic patients with (12 patients) or without (3 patients) neurological findings improved (3 cases after resection) or remained stable, and 2 patients worsened. Symptoms and examinations remained stable or improved in 8 (80%) of 10 patients with schwannomas and 3 (60%) of 5 patients with neurofibromas. Tumor volumes decreased in 12 (67%) of 18 tumors and increased in 3 tumors. Tumor volumes decreased in 8 of 10 schwannomas and 3 of 7 neurofibromas. Central necrosis developed in 8 (44%) of 18 tumors.

CONCLUSION

CyberKnife radiosurgery resulted in pain relief and functional preservation in selected foraminal peripheral nerve sheath tumors and a malignant peripheral nerve sheath tumor. Symptomatic and neurological improvements were more noticeable with schwannomas. Myelopathic symptoms may necessitate surgical debulking before radiosurgery.

Extracranial radiosurgery--applications in the management of benign intradural spinal neoplasms

Stereotactic radiosurgery has enabled the delivery of higher doses of radiation and decreased fractionation due to improved accuracy. Spinal radiosurgery has been increasingly utilized for the management of metastatic extradural spinal disease. However, surgical resection remains the primary treatment strategy for intradural spinal tumors. Preliminary evidence suggests that radiosurgical ablation with stereotactic radiation for intradural spinal lesions may be efficacious in certain clinical scenarios. Local tumor control, pain relief, and improvement in neurologic function with minimal morbidity have been reported in short-term follow-up. However, long-term efficacy of radiosurgery in the management of intradural spinal neoplasms necessitates further validation. As extracranial radiosurgery is a newly evolving modality, a continuative review of the current literature is appropriate. Until a standardized therapeutic window of safety and efficacy can be determined, the recommendation of radiosurgical applications for benign spinal tumors should be reserved for carefully selected cases.

CyberKnife radiosurgery for malignant spinal tumors: characterization of well-suited patients

STUDY DESIGN

A prospective interventional case-series study.

OBJECTIVE

To provide clinical results of CyberKnife fiducial-free spinal radiosurgery. The study focused on patients with no more than 2 malignant spinal tumors.

SUMMARY OF BACKGROUND DATA

Progress in frameless radiosurgical technology has enabled the application of radiosurgery to the spine. The CyberKnife System has been used extensively for spine radiosurgery. Until recently, the system required metallic fiducial implants for precise target tracking. Fiducial-free spinal radiosurgery with the CyberKnife has recently become possible, but until now clinical results obtained with this method had been limited.

METHODS

From August 2005 until October 2007, a consecutive series of 102 patients with a total of 134 malignant spinal tumors were selected for single-fraction, fiducial-free CyberKnife radiosurgery (CKRS). The study was limited to patients with a maximum of 2 tumors. Malignant primaries included breast cancer in 23 (22.6%) patients, renal cancer in 20 (19.6%) patients, gastro-intestinal cancers in 12 (11.8%) patients, prostate cancer each in 12 (11.8%) patients, lung cancer in 9 (8.9%) patients, sarcomas in 7 (6.9%) patients. A variety of other malignant tumors were found in 19 (18.6%) patients. Patients with spinal cord compression or evidence of myelopathy were excluded. The sequential neurologic status was recorded. Tumor-associated spinal pain was prospectively scored according to the visual analogue scale (VAS).

RESULTS

Of 102 individuals, 22 (21.6%) died due to progression of their systemic disease. Mean survival after CKRS was 1.4 years (CI: 1.2-1.6). Karnofsky performance score was the only independent predictor of survival after radiosurgery on log-rank test (P < 0.0001), and on Cox regression analysis (hazard ratio, 0.864, P < 0.0001, CI: 0.809-0.922). Median survival after initial tumor diagnosis was 18.4 years (CI: 15.1-23.4). Two (2%) patients suffered complications after radiosurgery; a tumor hemorrhage occurred in one, and another developed spinal instability. These and 2 other patients were stabilized by kyphoplasty. Neurotoxicity or myelopathy was not observed. Local tumor control 15 months after CKRS was 98% (95% CI: 89-99%). Tumor-associated pain was observed in 52 (51%) patients. In these patients the median pretreatment pain score of VAS = 7 (95% CI: 6-7) was significantly reduced to VAS = 1 (95% CI: 4-6) (P < 0.001) within 1 week after CKRS. Analysis of variance identified the initial pain score as the only significant variable to predict pain reduction after CKRS (P < 0.03). Pain recurrence in correlation with tumor recurrence was observed for 3 (6%) patients.

CONCLUSION

Spinal radiosurgery with the CyberKnife technology is a nonivasive, safe, and effective treatment method for patients with 1 or 2 small spinal malignant tumors. The best benefit of the treatment can be expected in patients with good to excellent clinical condition and patients with severe tumor associated pain.

Review of spinal radiosurgery: a minimally invasive approach for the treatment of spinal and paraspinal metastases

Intracranial radiosurgery has been proved effective for the treatment of brain metastasis. The treatment of paraspinal and spinal metastasis with spinal radiosurgery represents a natural extension of the principles of intracranial radiosurgery. However, spinal radiosurgery is a far more complicated process than intracranial radiosurgery. Larger treatment volumes, numerous organs at risk, and the inability to utilize rigid, frame-based immobilization all contribute to the substantially more complex process of spinal radiosurgery.

Beyond the convenience of a shorter duration of treatment for the patient, spinal radiosurgery affords a greater biological equivalent dose to a metastatic lesion than conventional radiotherapy fractionation schemes. This appears to translate into a high rate of tumor control and fast pain relief for patients. The minimally invasive nature of this approach is consistent with trends in open spinal surgery and helps to maintain or improve a patient's quality of life. Spinal radiosurgery has expanded the neurosurgical treatment armamentarium for patients with spinal and paraspinal metastasis.

Radiosurgery for benign intradural spinal tumors

OBJECTIVE

The role of stereotactic radiosurgery for the treatment of intracranial benign tumors is well established. There is less experience and more controversy regarding its use for benign tumors of the spine. This study evaluated the clinical efficacy of radiosurgery as part of the treatment paradigm of selected benign tumors of the spine.

METHODS

Seventy-three benign intradural extramedullary spinal tumors were treated with a radiosurgery technique and prospectively evaluated. Patient ages ranged from 18 to 85 years (mean age, 44 yr); the follow-up period was 8 to 71 months (median, 37 mo). Lesion location included 43 cervical, five thoracic, 19 lumbar, and six sacral. Tumor histology included neurofibroma (25 cases), schwannoma (35 cases), and meningioma (13 cases). Twenty-one cases were associated with neurofibromatosis Type 1, and nine patients had neurofibromatosis Type 2. Nineteen tumors (26%) had previously undergone open surgical resection, and six tumors (8%) had previously been treated with conventional external beam irradiation techniques.

RESULTS

Similar radiation doses were prescribed for all three histopathologies. The maximum intratumoral dose was 1500 to 2500 cGy (mean, 2164 Gy). Tumor volume ranged from 0.3 to 93.4 cm (mean, 10.5 cm; median, 4.11 cm). Radiosurgery was used for the treatment of postsurgical radiographic progression in 18 cases; it was used as the primary treatment modality in 14 cases; it was used for treatment of radiographic tumor progression in nine cases; and it was used for the treatment of postsurgical residual tumor in two cases. Long-term pain improvement occurred in 22 out of 30 cases (73%). Long-term radiographic tumor control was demonstrated in all cases. Three patients experienced new symptoms attributed to radiation-induced spinal cord toxicity 5 to 13 months after treatment.

CONCLUSION

Single fraction radiosurgery was found to be clinically effective for the treatment of benign extramedullary spinal neoplasms. Although surgical extirpation remains the primary treatment option for most benign spinal tumors, radiosurgery was demonstrated to have short-term clinical benefits for the treatment of such lesions. The long-term efficacy of spinal radiosurgery for such tumors will be determined with longer follow-up periods. Its role in patients with neurofibromatosis will also be further defined with greater clinical experience.