Intensity-modulated Stereotactic Radiotherapy of Paraspinal Tumors: A Preliminary Report

Re-irradiation spine stereotactic body radiotherapy following high-dose conventional radiotherapy for metastatic epidural spinal cord compression: a retrospective study

PURPOSE

 We aimed to evaluate the efficacy and safety of re-irradiation stereotactic body radiation therapy (SBRT) in patients with metastatic epidural spinal cord compression (MESCC) following high-dose conventional radiotherapy.

MATERIALS AND METHODS

 Twenty-one patients met the following eligibility criteria: with an irradiation history of 50 Gy2 equivalent dose in 2-Gy fractions (EQD2) or more, diagnosed MESCC in the cervical or thoracic spines, and treated with re-irradiation SBRT of 24 Gy in 2 fractions between April 2018 and March 2023. Prior treatment was radiotherapy alone, not including surgery. The primary endpoint was a 1-year local failure rate. Overall survival (OS) and treatment-related adverse events were assessed as the secondary endpoints. Since our cohort includes one treatment-related death (TRD) of esophageal perforation, the cumulative esophageal dose was evaluated to find the dose constraints related to severe toxicities.

RESULTS

 The median age was 68, and 14 males were included. The primary tumor sites (esophagus/lung/head and neck/others) were 6/6/7/2, and the median initial radiotherapy dose was 60 Gy2 EQD2 (range: 50-105 Gy2, 60-70/ > 70 Gy2 were 11/4). Ten patients underwent surgery followed by SBRT and 11 SBRT alone. At the median follow-up time of 10.4 months, 17 patients died of systemic disease progression including one TRD. No radiation-induced myelopathy or nerve root injuries occurred. Local failure occurred in six patients, with a 1-year local failure rate of 29.3% and a 1-year OS of 55.0%. Other toxicities included five cases of vertebral compression fractures (23.8%) and one radiation pneumonitis. The cumulative esophageal dose was recommended as follows: Dmax < 203, D0.035 cc < 187, and D1cc < 167 (Gy3 in biological effective dose).

CONCLUSION

 Re-irradiation spine SBRT may be effective for selected patients with cervical or thoracic MESCC, even with high-dose irradiation histories. The cumulative dose assessment across the original and re-irradiated esophagus was recommended to decrease the risk of severe esophageal toxicities.

Establishing the Swiss Spinal Tumor Registry (Swiss-STR): a prospective observation of surgical treatment patterns and long-term outcomes in patients with primary and metastatic spinal tumors

Background

Tumors of the vertebral column consist of primary spinal tumors and malignancies metastasizing to the spine. Although primary spine tumors are rare, metastases to the spine have gradually increased over past decades because of aging populations and improved survival for various cancer subtypes achieved by advances in cancer therapy. Metastases to the vertebral column occur in up to 70% of cancer patients, with 10% of patients demonstrating epidural spinal cord compression. Therefore, many cancer patients may face spinal surgical intervention during their chronic illness; such interventions range from simple cement augmentation over decompression of neural elements to extended instrumentation or spinal reconstruction. However, precise surgical treatment guidelines do not exist, likely due to the lack of robust, long-term clinical outcomes data and the overall heterogeneous nature of spinal tumors. Objectives of launching the Swiss Spinal Tumor Registry (Swiss-STR) are to collect and analyze high-quality, prospective, observational data on treatment patterns, clinical outcomes, and health-related quality of life (HRQoL) in adult patients undergoing spinal tumor surgery. This narrative review discusses our rationale and process of establishing this spinal cancer registry.

Methods

A REDCap-based registry was created for the standardized collection of clinical, radiographic, surgical, histological, radio-oncologial and oncological variables, as well as patient-reported outcome measures (PROMs).

Discussion

We propose that the Swiss-STR will inform on the effectiveness of current practices in spinal oncology and their impact on patient outcomes. Furthermore, the registry will enable better categorization of the various clinical presentations of spinal tumors, thereby facilitating treatment recommendations, defining the socio-economic burden on the healthcare system, and improving the quality of care. In cases of rare tumors, the multi-center data pooling will fill significant data gaps to yield better understanding of these entities. Finally, our two-step approach first implements a high-quality registry with efficient electronic data capture strategies across hospital sites in Switzerland, and second follows with potential to expand internationally, thus fostering future international scientific collaboration to further push the envelope in cancer research.

Radiotherapy and Surgical Advances in the Treatment of Metastatic Spine Tumors: A Narrative Review

Spine tumors encompass a wide range of diseases with a commensurately broad spectrum of available treatments, ranging from radiation for spinal metastases to highly invasive en bloc resection for primary vertebral column malignancies. This high variability in treatment approaches stems both from variability in the goals of surgery (e.g., oncologic cure vs. symptom palliation) and from the significant advancements in surgical technologies that have been made over the past 2 decades. Among these advancements are improvements in surgical technique, namely minimally invasive approaches, increased availability of focused radiation modalities (e.g., proton therapy and linear accelerator devices), and new surgical technologies, such as carbon fiber-reinforced polyether ether ketone rods. In addition, several groups have described nonsurgical interventions, such as vertebroplasty and kyphoplasty for spinal instability secondary to pathologic fracture, and lesion ablation with spinal laser interstitial thermoablation, radiofrequency ablation, or cryoablation. We provide an overview of the latest technological advancements in spinal oncology and their potential usefulness for modern spinal oncologists.

Factors associated with adjacent-level tumor progression in patients receiving surgery followed by radiosurgery for metastatic epidural spinal cord compression

OBJECTIVE

Separation surgery followed by spine stereotactic radiosurgery (SSRS) has been shown to achieve favorable rates of local tumor control and patient-reported outcomes in patients with metastatic epidural spinal cord compression (MESCC). However, rates and factors associated with adjacent-level tumor progression (ALTP) in this population have not yet been characterized. The present study aimed to identify factors associated with ALTP and examine its association with overall survival (OS) in patients receiving surgery followed by radiosurgery for MESCC.

METHODS

Thirty-nine patients who underwent separation surgery followed by SSRS for MESCC were identified using a prospectively collected database and were retrospectively reviewed. Radiological measurements were collected from preoperative, postoperative, and post-SSRS MRI. Statistical analysis was conducted using the Kaplan-Meier product-limit method and Cox proportional hazards test. Subgroup analysis was conducted for patients who experienced ALTP into the epidural space (ALTP-E).

RESULTS

The authors' cohort included 39 patients with a median OS of 14.7 months (range 2.07-96.3 months). ALTP was observed in 16 patients (41.0%) at a mean of 6.1 ± 5.4 months postradiosurgery, of whom 4 patients (10.3%) experienced ALTP-E. Patients with ALTP had shorter OS (13.0 vs 17.1 months, p = 0.047) compared with those without ALTP. Factors associated with an increased likelihood of ALTP included the amount of bone marrow infiltrated by tumor at the index level, amount of residual epidural disease following separation surgery, and prior receipt of radiotherapy at the index level (p < 0.05). Subgroup analysis revealed that primary tumor type, amount of preoperative epidural disease, time elapsed between surgery and radiosurgery, and prior receipt of radiotherapy at the index level were significantly associated with ALTP-E (p < 0.05).

CONCLUSIONS

To the authors' knowledge, this study is the first to identify possible risk factors for ALTP, and they suggest that it may be associated with shorter OS in patients receiving surgery followed by radiosurgery for MESCC. Future studies with higher power should be conducted to further characterize factors associated with ALTP in this population.

Minimally Invasive Pedicle Screw Fixation With Indirect Decompression by Ligamentotaxis in Pathological Fractures

BACKGROUND

The spine is the most common site of bony metastases. Associated pathological fractures can result in pain, neurological deficit, biomechanical instability, and deformity.

OBJECTIVE

To present a minimally invasive technique for indirect decompression by ligamentotaxis in pathological fractures.

METHODS

A minimally invasive approach was utilized to perform percutaneous pedicle screw fixation in patients who required stabilization for pathological fractures. Preoperative and postoperative computed tomography and magnetic resonance imaging were used to compare spinal canal area and midsagittal canal diameter.

RESULTS

Two patients with newly diagnosed pathological fractures underwent minimally invasive treatment. Each presented with minimal epidural disease and a chief complaint of intractable back pain without neurological deficit. They underwent minimally invasive pedicle screw fixation with indirect decompression by ligamentotaxis. In each case, postoperative imaging demonstrated an increase in spinal canal area and midsagittal canal diameter by an independent neuroradiologist. There were no perioperative complications, and each patient was neurologically stable without evidence of hardware failure at their 5- and 6-mo follow-up visits.

CONCLUSION

Minimally invasive percutaneous fixation can be used to stabilize pathological fractures and provide indirect decompression by ligamentotaxis. This procedure is associated with minimal blood loss, low morbidity, and rapid initiation of radiation therapy. Only patients with minimal epidural disease, stenosis caused primarily by bony retropulsion, and mild-to-moderate deformity should be considered candidates for this approach.

Population description and clinical response assessment for spinal metastases: part 2 of the SPIne response assessment in Neuro-Oncology (SPINO) group report

Background

Approximately 40% of metastatic cancer patients will develop spinal metastases. The current report provides recommendations for standardization of metrics used for spinal oncology patient population description and outcome assessment beyond local control endpoints on behalf of the SPIne response assessment in Neuro-Oncology (SPINO) group.

Methods

The SPINO group survey was conducted in order to determine the preferences for utilization of clinician-based and patient-reported outcome measures for description of patients with spinal metastases. Subsequently, ClinicalTrials.gov registry was searched for spinal oncology clinical trials, and measures for patient description and outcome reporting were identified for each trial. These two searches were used to identify currently used descriptors and instruments. A literature search was performed focusing on the measures identified in the survey and clinical trial search in order to assess their validity in the metastatic spinal tumor patient population. References for this manuscript were identified through PubMed and Medline searches.

Results

Published literature, expert survey, and ongoing clinical trials were used to synthesize recommendations for instruments for reporting of spinal stability, epidural tumor extension, neurological and functional status, and symptom severity.

Conclusions

Accurate description of patient population and therapy effects requires a combination of clinician-based and patient-reported outcome measures. The current report provides international consensus recommendations for the systematic reporting of patient- and clinician-reported measures required to develop trials applicable to surgery for spinal metastases and postoperative spine stereotactic body radiotherapy (SBRT).

Essential Concepts for the Management of Metastatic Spine Disease: What the Surgeon Should Know and Practice

STUDY DESIGN

Literature review.

OBJECTIVE

To provide an overview of the recent advances in spinal oncology, emphasizing the key role of the surgeon in the treatment of patients with spinal metastatic tumors.

METHODS

Literature review.

RESULTS

Therapeutic advances led to longer survival times among cancer patients, placing significant emphasis on durable local control, optimization of quality of life, and daily function for patients with spinal metastatic tumors. Recent integration of modern diagnostic tools, precision oncologic treatment, and widespread use of new technologies has transformed the treatment of spinal metastases. Currently, multidisciplinary spinal oncology teams include spinal surgeons, radiation and medical oncologists, pain and rehabilitation specialists, and interventional radiologists. Consistent use of common language facilitates communication, definition of treatment indications and outcomes, alongside comparative clinical research. The main parameters used to characterize patients with spinal metastases include functional status and health-related quality of life, the spinal instability neoplastic score, the epidural spinal cord compression scale, tumor histology, and genomic profile.

CONCLUSIONS

Stereotactic body radiotherapy revolutionized spinal oncology through delivery of durable local tumor control regardless of tumor histology. Currently, the major surgical indications include mechanical instability and high-grade spinal cord compression, when applicable, with surgery providing notable improvement in the quality of life and functional status for appropriately selected patients. Surgical trends include less invasive surgery with emphasis on durable local control and spinal stabilization.

Symptomatic aneurysmal bone cysts of the spine: clinical features, surgical outcomes, and prognostic factors

PURPOSE

The aim of the study was to report the long-term outcomes and analyze the potential prognostic factors that may contribute to symptomatic patients with aneurysmal bone cyst (ABC) of the spine undergoing surgical treatments.

METHODS

A retrospective analysis of consecutive patients with ABCs of the spine was performed. The clinical features were reviewed, and the disease-free survival (DFS) and overall survival (OS) rates were estimated using the Kaplan-Meier method. Factors with p values ≤ 0.05 were subjected to multivariate analysis by Cox proportional hazards model to identify the independent prognostic contributors. p values < 0.05 were considered statistically significant.

RESULTS

A total of 42 patients with ABCs of the spine were included in the study. All patients received surgical treatments. The mean follow-up period was 41.3 months (median 39.5, range 24-64). Local recurrence was detected in eight patients after surgery in our center, whereas death occurred in three patients. The estimated 5-year DFS and OS rate was 54.1% and 76.8%, respectively. The statistical analyses indicated that both en bloc resection and primary/secondary tumor status were independent prognostic factors for DFS.

CONCLUSIONS

Secondary ABC status may be associated with worse prognosis, and en bloc resection remains the treatment of choice for ABCs with neurologic deficits or spinal instability of the spine, which is correlated with better prognosis for local tumor control. These slides can be retrieved under Electronic Supplementary Material.

Advances in the treatment of metastatic spine tumors: the future is not what it used to be

An improved understanding of tumor biology, the ability to target tumor drivers, and the ability to harness the immune system have dramatically improved the expected survival of patients diagnosed with cancer. However, many patients continue to develop spine metastases that require local treatment with radiotherapy and surgery. Fortunately, the evolution of radiation delivery and operative techniques permits durable tumor control with a decreased risk of treatment-related toxicity and a greater emphasis on restoration of quality of life and daily function. Stereotactic body radiotherapy allows delivery of ablative radiation doses to the majority of spine tumors, reducing the need for surgery. Among patients who still require surgery for decompression of the spinal cord or spinal column stabilization, minimal access approaches and targeted tumor excision and ablation techniques minimize the surgical risk and facilitate postoperative recovery. Growing interdisciplinary collaboration among scientists and clinicians will further elucidate the synergistic possibilities among systemic, radiation, and surgical interventions for patients with spinal tumors and will bring many closer to curative therapies.

Improving accuracy for stereotactic body radiotherapy treatments of spinal metastases

PURPOSE

Use of SBRT techniques is now a relatively common recourse for spinal metastases due to good local control rates and durable pain control. However, the technique has not yet reached maturity for gantry-based systems, so work is still required in finding planning approaches that produce optimum conformity as well as delivery for the slew of treatment planning systems and treatment machines.

METHODS

A set of 32 SBRT spine treatment plans based on four vertebral sites, varying in modality and number of control points, were created in Pinnacle. These plans were assessed according to complexity metrics and planning objectives as well as undergoing treatment delivery QA on an Elekta VersaHD through ion chamber measurement, ArcCheck, film-dose map comparison and MLC log-file reconstruction via PerFraction.

RESULTS

All methods of QA demonstrated statistically significant agreement with each other (r = 0.63, P < 0.001). Plan complexity and delivery accuracy were found to be independent of MUs (r = 0.22, P > 0.05) but improved with the number of control points (r = 0.46, P < 0.03); with use of 90 control points producing the most complex and least accurate plans. The fraction of small apertures used in treatment had no impact on plan quality or accuracy (r = 0.29, P > 0.05) but rather more complexly modulated plans showed poorer results due to MLC leaf position inaccuracies. Plans utilizing 180 and 240 control points produced optimal plan coverage with similar complexity metrics to each other. However, plans with 240 control points demonstrated slightly better delivery accuracy, with fewer MLC leaf position discrepancies.

CONCLUSION

In contrast to other studies, MU had no effect on delivery accuracy, with the most impactful parameter at the disposal of the planner being the number of control points utilized.

DTI and pathological changes in a rabbit model of radiation injury to the spinal cord after 125I radioactive seed implantation

Excessive radiation exposure may lead to edema of the spinal cord and deterioration of the nervous system. Magnetic resonance imaging can be used to judge and assess the extent of edema and to evaluate pathological changes and thus may be used for the evaluation of spinal cord injuries caused by radiation therapy. Radioactive ¹²⁵I seeds to irradiate 90% of the spinal cord tissue at doses of 40–100 Gy (D90) were implanted in rabbits at T₁₀ to induce radiation injury, and we evaluated their safety for use in the spinal cord. Diffusion tensor imaging showed that with increased D90, the apparent diffusion coefficient and fractional anisotropy values were increased. Moreover, pathological damage of neurons and microvessels in the gray matter and white matter was aggravated. At 2 months after implantation, obvious pathological injury was visible in the spinal cords of each group. Magnetic resonance diffusion tensor imaging revealed the radiation injury to the spinal cord, and we quantified the degree of spinal cord injury through apparent diffusion coefficient and fractional anisotropy.

What Is the Effect of High-dose Radiation on Bone in Patients With Sacral Chordoma? A CT Study

BACKGROUND

Effects of high-dose radiation using protons and photons on bone are relatively unexplored, but high rates of insufficiency fractures are reported, and the causes of this are incompletely understood. Imaging studies with pre- and postradiation scans can help one understand the effect of radiation on bone.

QUESTIONS/PURPOSES

The purpose of this study was to assess the effects of high-dose radiation on the trabecular density of bone in the sacrum using CT-derived Hounsfield units (HU).

METHODS

Between 2009 and 2015, we treated 57 patients (older then 18 years) with sacral chordoma. Fourteen (25%) of them were treated with radiation only. The general indication for this approach is inoperability resulting from tumor size. Forty-two (74%) patients were treated with transverse sacral resections and high-dose radiotherapy (using either protons or photons or a combination) before surgery and after surgery. During this time period, our indication for this approach generally was symptomatic sacral chordoma in which resection would prevent further growth and reasonable sacrifice of nerve roots was possible. Of those patients, 21 (50%) had CT scans both before and after radiation treatment. We used HU as a surrogate for bone density. CT uses HU to derive information on tissue and bone quantity. A recent study presented reference HU values for normal (mean 133 ± 38 HU), osteoporotic (101 ± 25 HU), and osteopenic bone (79 ± 32 HU). To adjust for scanning protocol-induced changes in HU, we calculated the ratio between bone inside and outside the radiation field rather than using absolute values. To assess the effect of radiation, we tested whether there was a difference in ratio (sacrum/L1) before and after radiation. A control measurement was performed (L2/L1) and also tested for a difference before and after radiation. Statistical analyses were performed using the paired t-test.

RESULTS

The effects of radiation appeared confined to the intended field, because the bone density outside the treated field was not observed to decrease. The ratio of HU (a surrogate for bone density) in L2 relative to L1 did not change after radiotherapy (preradiation mean: 0.979 ± 0.009, postradiation mean: 0.980 ± 0.009, mean difference outside the radiation field: -0.001, 95% confidence interval [CI], -0.009 to 0.007, p = 0.799). The ratio of HU within the radiation field relative to L1 decreased after radiotherapy (preradiation mean: 0.895 ± 0.050, postradiation mean: 0.658 ± 0.050, mean difference inside the radiation field: 0.237, 95% CI, 0.187-0.287, p < 0.001), suggesting the bone density stayed the same outside the radiation field but decreased inside the radiation field.

CONCLUSIONS

Trabecular bone density decreased after high-dose radiation therapy in a small group of patients with sacral chordoma. High-dose radiation is increasingly gaining acceptance for treating sacral malignancies; further long-term prospective studies using calibrated CT scanners and preferably bone biopsies are needed.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Stereotactic radiosurgery for intradural spine tumors using cone-beam CT image guidance

OBJECTIVE

Cone-beam CT (CBCT) image guidance technology has been widely adopted for spine radiosurgery delivery. There is relatively little experience with spine radiosurgery for intradural tumors using CBCT image guidance. This study prospectively evaluated a series of intradural spine tumors treated with radiosurgery. Patient setup accuracy for spine radiosurgery delivery using CBCT image guidance for intradural spine tumors was determined.

METHODS

Eighty-two patients with intradural tumors were treated and prospectively evaluated. The positioning deviations of the spine radiosurgery treatments in patients were recorded. Radiosurgery was delivered using a linear accelerator with a beam modulator and CBCT image guidance combined with a robotic couch that allows positioning correction in 3 translational and 3 rotational directions. To measure patient movement, 3 quality assurance CBCTs were performed and recorded in 30 patients: before, halfway, and after the radiosurgery treatment. The positioning data and fused images of planning CT and CBCT from the treatments were analyzed to determine intrafraction patient movements. From each of 3 CBCTs, 3 translational and 3 rotational coordinates were obtained.

RESULTS

The radiosurgery procedure was successfully completed for all patients. Lesion locations included cervical (22), thoracic (17), lumbar (38), and sacral (5). Tumor histologies included schwannoma (27), neurofibromas (18), meningioma (16), hemangioblastoma (8), and ependymoma (5). The mean prescription dose was 17 Gy (range 12–27 Gy) delivered in 1–3 fractions. At the halfway point of the radiation, the translational variations and standard deviations were 0.4 ± 0.5, 0.5 ± 0.8, and 0.4 ± 0.5 mm in the lateral (x), longitudinal (y), and anteroposterior (z) directions, respectively. Similarly, the variations immediately after treatment were 0.5 ± 0.4, 0.5 ± 0.6, and 0.6 ± 0.5 mm along x, y, and z directions, respectively. The mean rotational angles were 0.3° ± 0.4°, 0.3° ± 0.4°, and 0.3° ± 0.4° along yaw, roll, and pitch, respectively, at the halfway point and 0.5° ± 0.5°, 0.4° ± 0.5°, and 0.2° ± 0.3° immediately after treatment.

CONCLUSIONS

Radiosurgery offers an alternative treatment option for intradural spine tumors in patients who may not be optimal candidates for open surgery. CBCT image guidance for patient setup for spine radiosurgery is accurate and successful in patients with intradural tumors.

Spine radiosurgery: lessons learned from the first 100 treatment sessions

OBJECTIVE

Local therapy to spine tumors has been shown to be effective in selected cases. Spinal radiosurgery (SRS) is an evolving radiotherapy regimen allowing for noninvasive, highly efficacious local treatment. The learning curve can compromise the results of any newly employed technology and should be studied to minimize its effects. In this paper the first 100 SRSs performed at several medical centers are presented and analyzed for the effects of the learning curve on outcome.

METHODS

A retrospective analysis was undertaken to evaluate data from patients treated with SRS at Sheba Medical Center and Assuta Medical Centers in the period from September 2011 to February 2016. Medical history, clinical and neurological findings, pathological diagnoses, SRS variables, complications, and follow-up data were collected and analyzed. Local control rates were calculated, and local treatment failure cases were qualitatively studied.

RESULTS

One hundred treatment sessions were performed for 118 lesions at 179 spinal levels in 80 patients. The complication rate was low and did not correlate with a learning curve. Mean follow-up time was 302 days, and the overall local control rate was 95%. The local control rate was dose dependent and increased from 87% (among 35 patients receiving a dose of 16 Gy) to 97% (among 65 patients receiving a dose of 18 Gy). The 6 treatment failure cases are discussed in detail.

CONCLUSIONS

Spinal radiosurgery is a safe and effective treatment. Comprehensive education of the treating team and continuous communication are essential to limit the effects of the learning curve on outcome.

En Bloc Resections in the Spine: The Experience of 220 Patients During 25 Years

BACKGROUND AND OBJECTIVE

En bloc resections aim at surgically removing a tumor in a single, intact piece. Approach must be planned for the complete removal of the tumor without violation of its margins. The shared knowledge of the morbidity, mortality, risk assessment for local disease recurrence, complications, and death, related to spine tumors excised en bloc could improve the treating physician's apprehension of the diseases and decision making process before, during, and after surgical treatment. The purpose of this study was to review and report the experience gained during 25 years in one of the world's biggest spine oncologic centers.

METHODS

A retrospective study of prospective collected data of 1681 patients affected by spine tumors, of whom 220 had en bloc resections performed.

RESULTS

Most tumors were primary-165 cases (43 benign and 122 malignant); metastases occurred in 55 patients. A total of 60 patients died from the disease and 33 local recurrences were recorded. A total of 153 complications were observed in 100 of 216 patients (46.2%); 64 of these patients (30%) suffered 1 complication, whereas the rest had 2 or more. All complications were categorized according to temporal distribution and severity. These were further divided into 7 groups according to the type of complication. There were 105 major and 48 minor complications. Seven patients (4.6%) died as a result of complications. There were 33 local recurrences (15.28%) recorded. Contaminated cases, surgical margins of the resected tumor-intralesional, marginal, and malignant tumors-were statistically significant independent risk factors for local recurrence of the tumor. Contamination, local recurrence, neoadjuvant radiotherapy, number of levels resected, and metastatic tumors compared with primary malignant tumor were shown to be independent risk factors for a patient's death.

CONCLUSIONS

Treatment of spinal aggressive benign and malignant bone tumors with en bloc resection is beneficial in terms of better local control and prognosis, although it is a highly demanding and risky procedure. Margins are the key point of this procedure, thus a careful preoperative oncologic and surgical staging is necessary to define the optimal surgical approach. The adverse event profile of these surgeries is high. Therefore, it should be performed by experienced and multidisciplinary teams in specialized high volume centers.

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.

Quantitative Evaluation of Local Control and Wound Healing Following Surgery and Stereotactic Spine Radiosurgery for Spine Tumors

OBJECTIVE

The present study evaluated the optimal measuring criteria to assess spinal tumor response to surgery followed by stereotactic spine radiosurgery (SRS) and reports the local control and wound complication rates following combined multimodality treatment.

METHODS AND MATERIALS

Prospectively collected patient information was retrospectively reviewed to identify patients treated with spine surgery followed by SRS. Tumor sizes and volumetric assessment were formally measured. Local control status was defined according to World Health Organization (WHO, bidimensional), RECIST (unidimensional), or volumetric size change. Statistical comparative assessments of tumor measurements were performed.

RESULTS

Twenty-two patients were eligible for evaluation after having undergone surgery followed by single-fraction SRS within a 2-month period. Seventeen had follow-up magnetic resonance imaging (MRI) with a mean patient follow-up of 12.59 months (range 3-36 months). None developed wound complication after radiation therapy (95% lower confidence bound 13%). Two patients had clinical recurrence while 15 of 17 achieved local control (88.3%). A test of marginal homogeneity for RECIST versus WHO was not statistically significant, P = 1.0 suggesting similar response classifications with both systems. Spearman correlations among 1) volumetric assessment, 2) bidimensional size, and 3) unidimensional size were significant for all groups (P < 0.05).

CONCLUSION

High local control rates can be achieved with surgery followed by SRS. Further, adjuvant SRS following spine tumor surgery delivers less radiation to the wound than conventional radiation and thus potentially reduces wound complications. Unidimensional, bidimensional, and volumetric tumor assessments demonstrate similar results. Hence the use of the simpler RECIST criteria is suitable and appropriate for evaluating the response to treatment after spine radiosurgery.

Prognostic factors associated with pain palliation after spine stereotactic body radiation therapy

OBJECT The number of patients with spinal tumors is rapidly increasing; spinal metastases develop in more than 30% of cancer patients during the course of their illness. Such lesions can significantly decrease quality of life, often necessitating treatment. Stereotactic radiosurgery has effectively achieved local control and symptomatic relief for these patients. The authors determined prognostic factors that predicted pain palliation and report overall institutional outcomes after spine stereotactic body radiation therapy (SBRT). METHODS Records of patients who had undergone treatment with SBRT for either primary spinal tumors or spinal metastases from June 2008 through June 2013 were retrospectively reviewed. Data were collected at the initial visit just before treatment and at 1-, 3-, 6-, and 12-month follow-up visits. Collected clinical data included Karnofsky Performance Scale scores, pain status, presence of neurological deficits, and prior radiation exposure at the level of interest. Radiation treatment plan parameters (dose, fractionation, and target coverage) were recorded. To determine the initial extent of epidural spinal cord compression (ESCC), the authors retrospectively reviewed MR images, assessed spinal instability according to the Bilsky scale, and evaluated lesion progression after treatment. RESULTS The study included 99 patients (mean age 60.4 years). The median survival time was 9.1 months (95% CI 6.9-17.2 months). Significant decreases in the proportion of patients reporting pain were observed at 3 months (p < 0.0001), 6 months (p = 0.0002), and 12 months (p = 0.0019) after treatment. Significant decreases in the number of patients reporting pain were also observed at the last follow-up visit (p = 0.00020) (median follow-up time 6.1 months, range 1.0-56.6 months). Univariate analyses revealed that significant predictors of persistent pain after intervention were initial ESCC grade, stratified by a Bilsky grade of 1c (p = 0.0058); initial American Spinal Injury Association grade of D (p = 0.011); initial Karnofsky Performance Scale score, stratified by a score of 80 (p = 0.002); the presence of multiple treated lesions (p = 0.044); and prior radiation at the site of interest (p < 0.0001). However, when multivariate analyses were performed on all variables with p values less than 0.05, the only predictor of pain at last follow-up visit was a prior history of radiation at the site of interest (p = 0.0038), although initial ESCC grade trended toward significance (p = 0.073). Using pain outcomes at 3 months, at this follow-up time point, pain could be predicted by receipt of radiation above a threshold biologically effective dose of 66.7 Gy. CONCLUSIONS Pain palliation occurs as early as 3 months after treatment; significant differences in pain reporting are also observed at 6 and 12 months. Pain palliation is limited for patients with spinal tumors with epidural extension that deforms the cord and for patients who have previously received radiation to the same site. Further investigation into the optimal dose and fractionation schedule are needed, but improved outcomes were observed in patients who received radiation at a biologically effective dose (with an a/b of 3.0) of 66.7 Gy or higher.

Dosimetric comparison of Acuros XB with collapsed cone convolution/superposition and anisotropic analytic algorithm for stereotactic ablative radiotherapy of thoracic spinal metastases

The aim of this study is to compare the recent Eclipse Acuros XB (AXB) dose calculation engine with the Pinnacle collapsed cone convolution/superposition (CCC) dose calculation algorithm and the Eclipse anisotropic analytic algorithm (AAA) for stereotactic ablative radiotherapy (SAbR) treatment planning of thoracic spinal (T‐spine) metastases using IMRT and VMAT delivery techniques. The three commissioned dose engines (CCC, AAA, and AXB) were validated with ion chamber and EBT2 film measurements utilizing a heterogeneous slab‐geometry water phantom and an anthropomorphic phantom. Step‐and‐shoot IMRT and VMAT treatment plans were developed and optimized for eight patients in Pinnacle, following our institutional SAbR protocol for spinal metastases. The CCC algorithm, with heterogeneity corrections, was used for dose calculations. These plans were then exported to Eclipse and recalculated using the AAA and AXB dose calculation algorithms. Various dosimetric parameters calculated with CCC and AAA were compared to that of the AXB calculations. In regions receiving above 50% of prescription dose, the calculated CCC mean dose is 3.1%–4.1% higher than that of AXB calculations for IMRT plans and 2.8%–3.5% higher for VMAT plans, while the calculated AAA mean dose is 1.5%–2.4% lower for IMRT and 1.2%–1.6% lower for VMAT. Statistically significant differences (p<0.05) were observed for most GTV and PTV indices between the CCC and AXB calculations for IMRT and VMAT, while differences between the AAA and AXB calculations were not statistically significant. For T‐spine SAbR treatment planning, the CCC calculations give a statistically significant overestimation of target dose compared to AXB. AAA underestimates target dose with no statistical significance compared to AXB. Further study is needed to determine the clinical impact of these findings.

PACS number: 87.55.D‐, 87.53.Ly

[Stereotactic radiotherapy for spinal meningiomas and neurinomas]

INTRODUCTION

Over the past decades, stereotactic conformal radiotherapy of intracranial meningiomas and schwannomas has been recognized as an effective and safe procedure. Due to the wide use of the CyberKnife system and the procedure of extracranial stereotactic radiotherapy and radiosurgery, the positive experience can be used to treat spinal tumors. This study assessed the effectiveness of stereotactic radiaotherapy of spinal meningiomas and neurinomas using the CyberKnife system.

MATERIAL AND METHODS

46 patients (34 females and 12 males) received treatment between November 2009 and December 2013 (65 tumor nodules). The median age of patients receiving radiotherapy was 49 years (range: 20 to 82 years). Twenty neoplasms were subjected to surgical treatment. In 11 patients, formation of the recurrent tumor foci following treatment was observed along with the systemic disease, neurofibromatosis. Six patients had multiple meningiomas. The median total dose of radiation therapy of neurinomas was 13.6 Gy (12.1-14.1 Gy) per fraction; up to 18.2 Gy (16.0-21.1 Gy) per three fractions; and up to 25.6 Gy (24.8-27.6 Gy) per five fractions. Higher doses were used for meningiomas: 15.9 Gy (14.1-16.2 Gy) per fraction; 20.9 Gy (19.5-21.1 Gy) per three fractions; and 27.5 Gy (25.0-29.9 Gy) per five fractions. The load to 0.15 cm3 of the spinal cord was no higher than the maximum permissible load of 12 Gy per fraction. The mean catamnestic follow-up was 18.1 (4-52) months: 21,1 (4-52) months for neurinomas and 18 (4-31) months for meningiomas. We have not observed complete tumor elimination (i.e., complete response to radiation therapy) in our series. Partial response was observed in 9 (13.8%) cases; stabilization was achieved in 54 (83.1%) cases; and tumor continued to grow in 2 (3.1%) cases. The patients' status was evaluated using the Frankel, the Karnofsky, and the VAS scales.

CONCLUSIONS

Our findings clearly demonstrate the short-term benefits of using CyberKnife radiotherapy for benign spinal cord tumors. The catamnestic follow-up needs to be extended to elaborate recommendations for radiation. The progress in this therapy type will considerably improve the quality of medical care provided to this cohort of patients.

Stereotactic radiosurgery for spinal metastases with or without separation surgery

OBJECT

In patients with significant epidural spinal cord compression, initial surgical decompression and stabilization of spinal metastases, as opposed to radical oncological resection, provides a margin around the spinal cord that facilitates subsequent treatment with high-dose adjuvant stereotactic radiosurgery (SRS). If a safe margin exists between tumor and spinal cord on initial imaging, then high-dose SRS may be used as the primary therapy, eliminating the need for surgery. Selecting the appropriate approach has shown greater efficacy of tumor control, neurological outcome, and duration of response when compared with external beam radiotherapy, regardless of tumor histology. This study evaluates the efficacy of this treatment approach in a series of 57 consecutive patients.

METHODS

Patients treated for spinal metastases between 2007 and 2011 using the Varian Trilogy Linear Accelerator were identified retrospectively. Each received SRS, with or without initial surgical decompression and instrumentation. Medical records were reviewed to assess neurological outcome and surgical or radiation-induced complications. Magnetic resonance images were obtained for each patient at 3-month intervals posttreatment, and radiographic response was assessed as stability/regression or progression. End points were neurological outcome and local radiographic disease control at death or latest follow-up.

RESULTS

Fifty-seven patients with 69 lesions were treated with SRS for spinal metastases. Forty-eight cases (70%) were treated with SRS alone, and 21 (30%) were treated with surgery prior to SRS. A single fraction was delivered in 38 cases (55%), while a hypofractionated scheme was used in 31 (45%). The most common histological entities were renal cell, breast, and lung carcinomas. Radiographically, local disease was unchanged or regressed in 63 of 69 tumors (91.3%). Frankel score improved or remained stable in 68 of 69 cases (98.6%).

CONCLUSIONS

SRS, alone or as an adjunct following surgical decompression, provides durable local radiographic disease control while preserving or improving neurological function. This less-invasive alternative to radical spinal oncological resection appears to be effective regardless of tumor histology without sacrificing durability of radiographic or clinical response.

Reoperation rates in the surgical treatment of spinal metastases

BACKGROUND CONTEXT

The surgical treatment in spinal metastases has been shown to improve function and neurologic outcome. Unplanned hospital readmissions can be costly and cause unnecessary harm.

PURPOSE

Our aim was to first analyze the reoperation rate and indications for this revision surgery in spinal metastases from an academic tertiary spinal institute and, second, to make comparisons on outcome (neurology and survival) against patients who underwent single surgery only.

STUDY DESIGN/SETTING

This was an ambispective review of all patients treated surgically over an 8-year period considering their neurologic and survival outcome data. Statistical analysis was performed using IBM SPSS 20. Because all scale values did not follow the normal distribution and significant outlier values existed, all descriptive statistics and comparisons were made using median values and the median test. Crosstabs and Pearson correlation were used to calculate differences between percentages and ordinal/nominal values. For two population proportions, the z test was used to calculate differences. The log-rank Mantel-Cox analysis was used to compare survival.

PATIENT SAMPLE

During the 8 years' study period, there were 384 patients who underwent urgent surgery for spinal metastasis. Of these, 289 patients were included who had sufficient information available. There were 31 reoperations performed (10.7%; mean age, 60 years; 13 male, 18 female). Exclusion criteria included patients treated solely by radiotherapy, patients who had undergone surgery for spinal metastasis before the study period, and those who had other causes for neurologic dysfunction such as stroke.

OUTCOME MEASURES

The outcomes considered in this study were revised Tokuhashi score, preoperative/postoperative Frankel scores, and survival.

METHODS

We performed an ambispective review of all patients treated surgically from our comprehensive database during the study period (October 2004 to October 2012). We reviewed all patient records on the database, including patient demographics and reoperation rates.

RESULTS

Reoperations were performed in the same admission in the majority of patients (n=20), whereas 11 patients had their second procedure in subsequent hospitalization. The reasons for their revision surgery were as follows: surgical site infection (SSI; 13 of 31 [42%]), failure of instrumentation (9 of 31 [29%]), local recurrence (5 of 31 [16%]), hematoma evacuation (2 of 31 [6%]), and others (2 of 31 [6%]).When comparing the "single surgery" and "revision surgery" groups, we found that the median preoperative and postoperative Frankel scores were similar at Grade 4 (range, 1-5) for both groups (preoperative, p=.92; postoperative, p=.87). However, 20 patients (8%) from the single surgery group and 7 (23%) from the revision group had a worse postoperative score, and this was significantly different (p=.01). No significant difference was found (p=.66) in the revised Tokuhashi score. The median number of survival days was similar (p=.719)-single surgery group: 250 days (range, 5-2,597 days) and revision group: 215 days (range, 9-1,352 days).

CONCLUSION

There was a modest reoperation rate (10.7%) in our patients treated surgically for spinal metastases over an 8-year period. Most of these were for SSI (42%), failure of instrumentation (26%), and local recurrence (16%). Patients with metastatic disease could benefit from revision surgery with comparable median survival rates but relatively poorer neurologic outcomes. This study may help to assist with informed decision making for this vulnerable patient group.

CT-guidance interstitial (125)Iodine seed brachytherapy as a salvage therapy for recurrent spinal primary tumors

Background

Management of spinal neoplasms has relied on open surgery and external beam radiotherapy (EBRT). Although primary spinal tumors are rare, their treatment remains a pervasive problem. This analysis sought to evaluate the safety and efficacy of CT-guided ¹²⁵I seed brachytherapy for recurrent paraspinous and vertebral primary tumors.

Methods

From November 2002 to June 2014, 17 patients who met the inclusion criteria were retrospectively reviewed. 14 (82.4%) had previously undergone surgery, 15 (88.2%) had received conventional EBRT and 3 (17.6%) had chosen chemotherapy. The number of ¹²⁵I seeds implanted ranged from 7 to 122 (median 79) with specific activity of 0.5-0.8 mCi (median 0.7 mCi). The post-plan showed that the actuarial D₉₀ of ¹²⁵I seeds were 90–183 Gy (median 137 Gy). The follow-up period ranged from 2 to 69 months (median 19 months). The local control rate was calculated by the Kaplan-Meier method.

Results

For 5 Chondrosarcomas, the 1-, 2-, 3-year local control rates were 75%, 37.5%, and 37.5%, respectively, with a median of 34 months (range, 4–39 months). For 4 chordomas, the local control rate was 50% with a median follow-up of 13 months (range, 3–17 months). For 3 fibromatosis, all of them were survival without local recurrence at the end of follow-up. During the follow-up period, 35.3% (6/17) died from metastases, 17.6% (3/17) developed local recurrence by 8, 14 and 34 months while 64.7% (11/17) remained alive. 100% experienced pain relief and normal or improved ambulation, without more than Frankel grade 3 radiation myelopathy.

Conclusions

Percutaneous ¹²⁵I seed implantation can be an alternative or retreatment for recurrent spinal primary tumors.

New therapeutics in spine metastases

The number of patients who will develop metastatic spinal tumors is estimated to be between 5 and 10% of all cancer patients. As the therapy for systemic cancer improves, the number of patients developing symptomatic spinal tumors that require local therapy will increase. Over the last 10 years there has been a dramatic evolution in our ability to treat spinal tumors. These advances have not only been created by improvements in surgical techniques and instrumentation, but also developments in radiographic imaging, radiation therapy and chemotherapy. It is important for spine surgeons, radiologists, and radiation and medical oncologists to continue developing techniques for spinal salvage that will improve pain relief, achieve mechanical stability, improve or maintain neurologic function and sustain local tumor control. The evolution of these technologies will help to provide palliation and improve quality of life for patients with metastatic disease.

Stereotactic radiosurgery and radiation therapy for spinal tumors

Spinal tumors constitute 15% of all CNS neoplasms. Radiation therapy can be administered for palliation of pain and spinal cord compression. However, the amount of radiation that can be administered is often limited by the tolerance of the spinal cord, especially in cases where prior radiation therapy has been given. Stereotactic radiosurgery and radiotherapy allow the delivery of a higher dose of radiation to spinal lesions, while limiting the spinal cord dose to below the tolerance level. These are technically demanding procedures and should be performed only when proper equipment and expertise are available. Data on spinal stereotactic radiosurgery and radiotherapy have emerged in recent years. This review summarizes the clinical applications of stereotactic radiosurgery and radiotherapy for spinal tumors.

Accuray CyberKnife®image-guided radiosurgical system

Radiosurgery is the application of radiation therapy in an extremely precise manner. These techniques apply large bioequivalent doses of radiation to a small area in order to destroy tumor cells, while sparing surrounding normal tissues. Radiosurgery has been available for intracranial abnormalities since the 1950s but it has only recently become available to treat tumors outside of the brain and skull base. This article outlines the authors experience with CyberKnife in the treatment of spinal and spine-associated abnormalities.

Intradural extramedullary benign spinal lesions radiosurgery. Medium- to long-term results from a single institution experience

BACKGROUND

Surgery represents the first-choice treatment for spinal intradural tumours. On the other hand, whether it is most appropriate in the setting of recurrences, residual or multiple lesions remains an open question. Moreover, some patients are less than ideal candidates for surgery. In this study we report about our own radiosurgery experience in the treatment of benign intradural extramedullary tumours of the spine.

METHODS

In our study we analyzed the outcomes for 18 patients (21 lesions) treated for benign intradural extramedullary lesions, with a minimum follow-up period of 32 months. The lesions included 11 meningiomas, 9 schwannomas and 1 neurofibroma.

RESULTS

The mean follow-up was 43 months (32-73 months). The median tumour volume was 2 cc (0.2-17.7 cc). Eleven lesions underwent single-fraction treatment (mean prescribed dose ranging from 10 to 13 Gy). The others received a multisession radiosurgery treatment (4-6 fractions) with a mean prescription dose ranging from 18.5 to 25 Gy. The maximum dose to the spinal cord ranged from 9.2 to 26 Gy. During the follow-up period, none of the lesions showed radiological evidence of progression. Neurological status was preserved or improved and no permanent sequelae were observed. Significant and durable pain relief was observed.

CONCLUSIONS

Although surgical excision remains the primary treatment option for most intradural tumours, radiosurgery offers a real alternative therapeutic modality, especially in case of recurrent and residual lesions or when surgery is contraindicated.

A multi-national report on methods for institutional credentialing for spine radiosurgery

BACKGROUND

Stereotactic body radiotherapy and radiosurgery are rapidly emerging treatment options for both malignant and benign spine tumors. Proper institutional credentialing by physicians and medical physicists as well as other personnel is important for the safe and effective adoption of spine radiosurgery. This article describes the methods for institutional credentialing for spine radiosurgery at seven highly experienced international institutions.

METHODS

All institutions (n = 7) are members of the Elekta Spine Radiosurgery Research Consortium and have a dedicated research and clinical focus on image-guided spine radiosurgery. A questionnaire consisting of 24 items covering various aspects of institutional credentialing for spine radiosurgery was completed by all seven institutions.

RESULTS

Close agreement was observed in most aspects of spine radiosurgery credentialing at each institution. A formal credentialing process was believed to be important for the implementation of a new spine radiosurgery program, for patient safety and clinical outcomes. One institution has a written policy specific for spine radiosurgery credentialing, but all have an undocumented credentialing system in place. All institutions rely upon an in-house proctoring system for the training of both physicians and medical physicists. Four institutions require physicians and medical physicists to attend corporate sponsored training. Two of these 4 institutions also require attendance at a non-corporate sponsored academic society radiosurgery course. Corporate as well as non-corporate sponsored training were believed to be complimentary and both important for training. In 5 centers, all cases must be reviewed at a multidisciplinary conference prior to radiosurgery treatment. At 3 centers, neurosurgeons are not required to be involved in all cases if there is no evidence for instability or spinal cord compression. Backup physicians and physicists are required at only 1 institution, but all institutions have more than one specialist trained to perform spine radiosurgery. All centers believed that credentialing should also be device specific, and all believed that professional societies should formulate guidelines for institutions on the requirements for spine radiosurgery credentialing. Finally, in 4 institutions radiation therapists were required to attend corporate-sponsored device specific training for credentialing, and in only 1 institution were radiation therapists required to also attend academic society training for credentialing.

CONCLUSIONS

This study represents the first multi-national report of the current practice of institutional credentialing for spine radiosurgery. Key methodologies for safe implementation and credentialing of spine radiosurgery have been identified. There is strong agreement among experienced centers that credentialing is an important component of the safe and effective implementation of a spine radiosurgery program.

Intraoperative 32P High-Dose Rate Brachytherapy of the Dura for Recurrent Primary and Metastatic Intracranial and Spinal Tumors

BACKGROUND:

Treatment of spinal and intracranial tumors with dural involvement is complicated by radiation tolerance of sensitive structures, especially in the setting of previous treatment.

OBJECTIVE:

To evaluate whether intraoperative brachytherapy with short-range sources allows therapeutic dose delivery without damaging sensitive structures.

METHODS:

The median doses of previous treatment were 3000 cGy (range, 1800-7200 cGy) for 8 patients with primary/recurrent and 17 patients with metastatic spinal tumors and 5040 cGy (range, 1300-6040 cGy) for 5 patients with locally recurrent and 2 patients with metastatic intracranial tumors. Patients underwent gross total or maximal resection of the tumor and were then treated with an intraoperative brachytherapy plaque consisting of a flexible silicone film incorporating 32P. A dose of 1000 cGy was delivered to a depth of 1 mm; the percent depth dose was less than 1% at 4 mm from the prescription depth. Median postoperative radiation doses of 2700 cGy (range, 1800-3000 cGy) were delivered to 15 spinal tumor patients and 3000 cGy (range, 1800-3000 cGy) to 3 intracranial tumor patients. The median follow-up was 4.4 months (range, 2.6-23.3 months) for spinal tumor patients and 5.3 months (range, 0.7-16.2) for intracranial tumor patients.

RESULTS:

At 6-month follow-up, for all spinal tumor patients, local progression-free survival and overall survival rates were both 83.3% (95% confidence interval [CI]: 62.3%-94.3%); for all intracranial tumor patients, the local progression-free survival rate was 62.5% (95% CI: 23.8%-90.9%) and the overall survival rate was 66.7% (95% CI: 26.7%-92.9%). There were no intraoperative or postoperative complications secondary to radiotherapy.

CONCLUSION:

Use of the 32P brachytherapy plaque is technically simple and not associated with increased risk of complications, even after multiple radiation courses. Local control rates were more than 80% in patients with proven radiation-resistant spinal disease.

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.

Marginal recurrence requiring salvage radiotherapy after stereotactic body radiotherapy for spinal metastases

INTRODUCTION

We sought to quantify and identify risk factors associated with margin recurrence (MR) requiring salvage radiotherapy after stereotactic body radiation therapy (SBRT) for spinal metastases.

METHODS

We retrospectively reviewed patients with spinal metastases who were treated with single-fraction SBRT between 2006 and 2009. Gross tumor was contoured, along with either the entire associated vertebral body(ies) or the posterior elements, and included in the planning target volume. No additional margins were used. MR was defined as recurrent tumor within one vertebral level above or below the treated lesion that required salvage radiotherapy. Only patients who presented for 3-month post-SBRT follow-up were included in the analysis. Fine and Gray competing risk regression models were generated to identify variables associated with higher risks of MR. MR was plotted using cumulative incidence analysis.

RESULTS

SBRT was delivered to 208 lesions in 149 patients. Median follow-up was 8.6 months, and median survival was 12.8 months. The median prescribed dose was 14 Gy (10-16 Gy). MR occurred in 26 (12.5%) treated lesions, at a median time of 7.7 months after SBRT. Patients with paraspinal disease at the time of SBRT (20.8% vs. 7.6% of patients; p = 0.02), and those treated with <16 Gy (16.3% vs. 6.3% of patients, p = 0.14) had higher rates of MR. Both variables were associated with significantly higher risk of MR on multivariate analysis.

CONCLUSION

SBRT for spinal metastases results in a low overall rate of MR. The presence of paraspinal disease at the time of SBRT and a dose of <16 Gy were associated with higher risks of MR.

Aneurysmal bone cyst secondary to giant cell tumor of the mobile spine: a report of 11 cases

STUDY DESIGN

A retrospective analysis was performed.

OBJECTIVE

To analyze the characteristics of aneurysmal bone cyst arising from giant cell tumor of the mobile spine and to discuss the outcome of corresponding surgical and nonsurgical treatment.

SUMMARY OF BACKGROUND DATA

Giant cell tumors are generally benign neoplasms that exhibit aggressive behavior with a tendency to recur locally. Aneurysmal bone cysts are benign, highly vascular osseous lesions. Although both of them have been described separately in previous literatures, few reports have described aneurysmal bone cyst secondary to giant cell tumor of the mobile spine.

METHODS

Between January 2004 and December 2009, 11 patients were identified with an aneurysmal bone cyst arising from giant cell tumor of the mobile spine. Four patients underwent subtotal tumor resection followed by radiotherapy, and the other 7 patients underwent total tumor resection. Patients with lesions located below T6 were treated with selective arterial embolization before surgery. Clinical data and the efficacy of surgery were analyzed via chart review

RESULTS

Of the eleven patients identified for inclusion in this study, the average age was 33 months (range ∇ 14-65 months). The mean length of follow-up was 31 months. Seven patients kept disease-free during the follow-ups. The remaining four patients recurred and one died of local re-recurrence and lung metastasis.

CONCLUSION

Unlike primary aneurysmal bone cyst, secondary aneurysmal bone cyst arising from giant cell tumor of the mobile spine has a more aggressive tendency to recurrence locally. Complete resection with systematic radiotherapy should be undertaken for the treatment of aneurysmal bone cyst secondary to giant cell tumor of the mobile spine, which is associated with a good prognosis for local tumor control. As complete or as radical an operation as possible should be performed at first presentation. The best chance for the patient is the first chance. Selective preoperative embolization is advised to minimize intraoperative blood loss.

Stereotactic body radiation therapy: the report of AAPM Task Group 101

Task Group 101 of the AAPM has prepared this report for medical physicists, clinicians, and therapists in order to outline the best practice guidelines for the external-beam radiation therapy technique referred to as stereotactic body radiation therapy (SBRT). The task group report includes a review of the literature to identify reported clinical findings and expected outcomes for this treatment modality. Information is provided for establishing a SBRT program, including protocols, equipment, resources, and QA procedures. Additionally, suggestions for developing consistent documentation for prescribing, reporting, and recording SBRT treatment delivery is provided.

Repeat decompression surgery for recurrent spinal metastases

Object

In this paper, the authors' goal was to determine the outcome of reoperation for recurrent epidural spinal cord compression in patients with metastatic spine disease.

Methods

A retrospective chart review was conducted of all patients who underwent spine surgery at the Memorial Sloan-Kettering Cancer Center between 1996 and 2007. Thirty-nine patients who underwent reoperation of the spine at the level previously treated with surgery were identified. Only patients whose reoperation was performed because of tumor recurrence leading to high-grade epidural spinal cord compression or recurrence with no further radiation options were included in the study. Patients who underwent reoperations exclusively for instrumentation failure were excluded. All patients underwent additional decompression via a posterolateral approach without removal of the spinal instrumentation.

Results

Patients underwent 1–4 reoperations at the same level. A median survival time of 12.4 months was noted after the first reoperation, and a median survival time of 9.1 months was noted after the last reoperation. At last follow-up 22 (65%) of 34 patients were ambulatory at the time of last follow-up or death, and the median time between loss-of-ambulation and death was 1 month. Functional status was maintained or improved by one Eastern Cooperative Oncology Group grade in 97% of patients. A major surgical complication rate of 5% was noted.

Conclusions

Reoperation represents a viable option in patients with high-grade epidural spinal cord compression who have recurrent metastatic tumors at previously operated spinal levels. In carefully selected patients, reoperation can prolong ambulation and result in good functional and neurological outcomes.

Spine metastases: current treatments and future directions

Spinal metastases are the most frequently encountered spinal tumour and can affect up to 50% of cancer patients. Both the incidence and prevalence of metastases are thought to be rising due to better detection and treatment options of the systemic malignancy resulting in increased patient survival. Further, the development and access to newer imaging modalities have resulted in easier screening and diagnosis of spine metastases. Current evidence suggests that pain, neurological symptoms and quality of life are all improved if patients with spine metastases are treated early and aggressively. However, selection of the appropriate therapy depends on several factors including primary histology, extent of the systemic disease, existing co-morbidities, prior treatment modalities, patient age and performance status, predicted life expectancy and available resources. This article reviews the currently available therapeutic options for spinal metastases including conventional external beam radiation therapy, open surgical decompression and stabilisation, vertebral augmentation and other minimally invasive surgery (MIS) options, stereotactic spine radiosurgery, bisphosphonates, systemic radioisotopes and chemotherapy. An algorithm for the management of spine metastases is also proposed. It outlines a multidisciplinary and integrated approach to these patients and it is hoped that this along with future advances and research will result in improved patient care and outcomes.

Setup accuracy of spine radiosurgery using cone beam computed tomography image guidance in patients with spinal implants

OBJECT

Cone beam computed tomography (CBCT) image guidance technology has been adopted for use in spine radiosurgery. There is concern regarding the ability to safely and accurately perform spine radiosurgery without the use of implanted fiducials for image guidance in postsurgical cases in which titanium instrumentation and/or methylmethacrylate (MMA) has been implanted. In this study the authors prospectively evaluated the accuracy of the patient setup for spine radiosurgery by using CBCT image guidance in the context of orthopedic hardware at the site of disease.

METHODS

The positioning deviations of 31 single-fraction spine radiosurgery treatments in patients with spinal implants were prospectively evaluated using the Elekta Synergy S 6-MV linear accelerator with a beam modulator and CBCT image guidance combined with a robotic couch that allows positioning correction in 3 translational and 3 rotational directions. To measure patient movement, 3 quality-assurance CBCT studies were performed and recorded: before, halfway through, and after radiosurgical treatment. The positioning data and fused images of planning CTs and CBCTs from the treatments were analyzed to determine intrafractional patient movements. From each of 3 CBCTs, 3 translational and 3 rotational coordinates were obtained.

RESULTS

The prescribed dose to the gross tumor volume for the cohort was 12-18 Gy (mean 14 Gy) utilizing 9-14 coplanar intensity-modulated radiation therapy (IMRT) beams (mean 10 beams). At the halfway point of the radiosurgery, the translational variations and standard deviations were 0.6 +/- 0.6, 0.4 +/- 0.4, and 0.5 +/- 0.5 mm in the lateral (X), longitudinal (Y), and anteroposterior (Z) directions, respectively. The magnitude of the 3D vector (X,Y,Z) was 1.1 +/- 0.7 mm. Similarly, the variations immediately after treatment were 0.5 +/- 0.3, 0.4 +/- 0.4, and 0.5 +/- 0.6 mm along the X, Y, and Z directions, respectively. The 3D vector was 1.0 +/- 0.6 mm. The mean rotational angles were 0.3 +/- 0.4, 0.5 +/- 0.6, and 0.3 +/- 0.4 degrees along yaw, roll, and pitch, respectively, at the halfway point and 0.3 +/- 0.4, 0.6 +/- 0.6, and 0.4 +/- 0.5 degrees immediately after treatment.

CONCLUSIONS

Cone beam CT image guidance used for patient setup for spine radiosurgery was highly accurate despite the presence of spinal instrumentation and/or MMA at the level of the target volume. The presence of such spinal implants does not preclude safe treatment via spine radiosurgery in these patients.

Correlation of local failure with measures of dose insufficiency in the high-dose single-fraction treatment of bony metastases

PURPOSE

In the setting of high-dose single-fraction image-guided radiotherapy of spine metastases, the delivered dose is hypothesized to be a significant factor in local control. We investigated the dependence of local control on measures of dose insufficiency.

METHODS AND MATERIALS

The minimum doses received by the hottest 100%, 98%, and 95% (D(min), D(98), and D(95)) of the gross target volume (GTV) were computed for 91 consecutively treated lesions observed in 79 patients. Prescribed doses of 18-24 Gy were delivered in a single fraction. The spinal cord and cauda equina were constrained to a maximum dose of 12-14 Gy and 16 Gy, respectively. A rank-sum test was used to assess the differences between radiographic local failure and local control.

RESULTS

With a median follow-up of 18 months, seven local failures have occurred. The distributions of GTV D(min), D(98), and D(95) for treatments resulting in local failure were found to be statistically different from the corresponding distributions of the patient group as a whole. Taking no account of histology, p values calculated for D(min), D(98), and D(95) were 0.004, 0.012, and 0.031, respectively. No correlations between local failure and target volume or between local failure and anatomic location were found.

CONCLUSIONS

The results indicate that D(min), D(98), and D(95) may be important risk factors for local failure. No local failures in any histology were observed when D(min) was >15 Gy, suggesting that this metric may be an important predictor of local control.

Stereotactic body radiotherapy: a review

Stereotactic body radiotherapy (SBRT) combines the challenge of meeting the stringent dosimetric requirements of stereotactic radiosurgery with that of accounting for the physiological movement of tumour and normal tissue. Here we present an overview of the history and development of SBRT and discuss the radiobiological rationale upon which it is based. The published results of SBRT for lung, liver, pancreas, kidney, prostate and spinal lesions are reviewed and summarised. The current evidence base is appraised and important ongoing trials are identified.