Vertebral compression fracture risk after stereotactic body radiotherapy for spinal metastases

Delayed vertebral body collapse after stereotactic radiosurgery and radiofrequency ablation: Case report with histopathologic-MRI correlation

Stereotactic radiosurgery and percutaneous radiofrequency ablation are emerging therapies for pain palliation and local control of spinal metastases. However, the post-treatment imaging findings are not well characterized and the risk of long-term complications is unknown. We present the case of a 46-year-old woman with delayed vertebral body collapse after stereotactic radiosurgery and radiofrequency ablation of a painful lumbar metastasis. Histopathologic-MRI correlation confirmed osteonecrosis as the underlying etiology and demonstrated that treatment-induced vascular fibrosis and tumor progression can have identical imaging appearances.

[Kyphoplasty combined with intraoperative radiotherapy (Kypho-IORT). Alternative therapy for patients with oligometastatic spinal metastases]

BACKGROUND

Due to a more effective systemic therapy the survival of patients suffering from malignant tumors has been significantly improved but a longer life span is often associated with a higher incidence of osseous metastases. The majority of these metastases are localized in the spine causing pain, instability and neurological impairments. The interdisciplinary management of spinal metastases previously consisted of stabilization followed by fractionated external body radiation therapy. A reduction in procedural severity and morbidity as well as consideration of self-sufficiency and hospitalization time are important target parameters for these palliative patients.

METHOD AND RESULTS

Kyphoplasty combined with intraoperative radiotherapy (Kypho-IORT) is one of several modern treatment options, which involves a minimally invasive procedure with local high-dose transpedicular irradiation of the spine with low-energy (50 kV) X-rays. Immediately following irradiation, stabilization of the spine is carried out using kyphoplasty via the same access route so that a single stage procedure with excellent pain reduction and good local tumor control can be achieved. This article presents clinical data for this procedure and the different fields of indications are critically reviewed and compared to other therapy options. Methodological improvements and options for further individualization of therapy are demonstrated.

CONCLUSION

The Kypho-IORT procedure is a safe, feasible and beneficial modern treatment option for instant stabilization and local tumor control in patients with spinal metastases. More than 100 operations have been successfully performed so that the method can be deemed suitable for inclusion in the clinical routine. A phase II dose escalation study has now been completed and submitted for publication and a 2-arm non-inferiority trial (phase III study) for comparison with conventional irradiation is in progress.

Clinical outcomes of stereotactic body radiotherapy for spinal metastases from hepatocellular carcinoma

Purpose

To investigate the outcomes of patients with spinal metastases from hepatocellular carcinoma (HCC), who were treated by stereotactic body radiotherapy (SBRT).

Materials and Methods

This retrospective study evaluated 23 patients who underwent SBRT from October 2008 to August 2012 for 36 spinal metastases from HCC. SBRT consisted of approximately 2 fractionation schedules, which were 18 to 40 Gy in 1 to 4 fractions for group A lesions (n = 15) and 50 Gy in 10 fractions for group B lesions (n = 21).

Results

The median follow-up period was 7 months (range, 2 to 16 months). Seven patients developed grade 1 or 2 gastrointestinal toxicity, and one developed grade 2 leucopenia. Compression fractures occurred in association with 25% of the lesions, with a median time to fracture of 2 months. Pain relief occurred in 92.3% and 68.4% of group A and B lesions, respectively. Radiologic response (complete and partial response) occurred in 80.0% and 61.9% of group A and B lesions, respectively. The estimated 1-year spinal-tumor progression-free survival rate was 78.5%. The median overall survival period and 1-year overall survival rate were 9 months (range, 2 to 16 months) and 25.7%, respectively.

Conclusion

SBRT for spinal metastases from HCC is well tolerated and effective at providing pain relief and radiologic response. Because compression fractures develop at a high rate following SBRT for spinal metastases from primary HCC, careful follow up of the patient is required.

Single versus multiple session stereotactic body radiotherapy for spinal metastasis: the risk-benefit ratio

Spine stereotactic body radiation therapy represents an important advancement in the management of spinal metastases that allows precise delivery of ablative doses of radiation therapy with excellent local control. Although the technique is being increasingly used in clinical practice, the optimal fractionation schedule remains uncertain. In this perspective paper, we review radiobiologic principles that support the use of multiple- versus single-fraction spine stereotactic body radiation therapy schedules and clinical data supporting the multiple-fraction approach. Specifically, we suggest that there may be a local control benefit of fractionation, while helping to limit the risk of toxicities such as vertebral body fracture, pain flare and radiation myelopathy. We conclude with future directions and the need for future study on this important topic.

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.

Technique and early clinical outcomes for spinal and paraspinal tumours treated with stereotactic body radiotherapy

We report technique and early clinical results of stereotactic body radiotherapy (SBRT) from Princess Alexandra Hospital. SBRT involves the precise delivery of highly conformal and image-guided external beam radiotherapy with high doses per fraction. It is increasingly being applied in management of spinal tumours. Thirty-six courses of spine SBRT in 34 patients were delivered between May 2010 and December 2013. Mean patient age was 58 years. Treatment was predominantly for metastatic disease, applied in de novo (n=22), retreatment (n=14) and postoperative (n=8) settings. Prescribed doses included 18-30 Gy in 1-5 fractions. SBRT technique evolved during the study period, resulting in a relative dose escalation. No severe acute toxicities were observed. At median follow-up of 7.4 months (range: 1.7-22.2), no late radiation myelopathy was observed. Risk of new/worsening vertebral compression fractures was 22% (n=8) and was significantly associated with increasing Spinal Instability Neoplastic Scores (p=0.0002). In-field control was 86% with relapse occurring at a median interval of 2.8 months (range: 1.9-4.7). Thirteen patients (36%) died and median overall survival has not been reached. SBRT is an evolving technology with promising early efficacy and safety results. The outcomes of this series are comparable with international literature, and await longer follow-up.

Five-Year Outcomes of High-Dose Single-Fraction Spinal Stereotactic Radiosurgery

PURPOSE

To characterize local tumor control and toxicity risk in very long-term survivors (>5 years) after high-dose spinal image guided, intensity modulated radiation therapy delivered as single-dose stereotactic radiosurgery (SRS). Previously published spinal SRS outcome analyses have included a heterogeneous population of cancer patients, mostly with short survival. This is the first study reporting the long-term tumor control and toxicity profiles after high-dose single-fraction spinal SRS.

METHODS AND MATERIALS

The study population included all patients treated from June 2004 to July 2009 with single-fraction spinal SRS (dose 24 Gy) who had survived at least 5 years after treatment. The endpoints examined included disease progression, surgical or radiation retreatment, in-field fracture development, and radiation-associated toxicity, scored using the Radiation Therapy Oncology Group radiation morbidity scoring criteria and the Common Terminology Criteria for Adverse Events, version 4.0. Local control and fracture development were assessed using Kaplan-Meier analysis.

RESULTS

Of 278 patients, 31 (11.1%), with 36 segments treated for spinal tumors, survived at least 5 years after treatment and were followed up radiographically and clinically for a median of 6.1 years (maximum 102 months). The histopathologic findings for the 5-year survivors included radiation-resistant metastases in 58%, radiation-sensitive metastases in 22%, and primary bone tumors in 19%. In this selected cohort, 3 treatment failures occurred at a median of 48.6 months, including 2 recurrences in the radiation field and 1 patient with demonstrated progression at the treatment margins. Ten lesions (27.8%) were associated with acute grade 1 cutaneous or gastrointestinal toxicity. Delayed toxicity ≥ 3 months after treatment included 8 cases (22.2%) of mild neuropathy, 2 (5.6%) of gastrointestinal discomfort, 8 (22.2%) of dermatitides, and 3 (8.3%) of myalgias/myositis. Thirteen treated levels (36.1%) in 12 patients demonstrated progressive vertebral body collapse or endplate fractures at a median of 25.7 months (range 11.6-76.0), of which 5 (14%) became symptomatic and subsequently required percutaneous cement augmentation or surgery.

CONCLUSIONS

In the longest-term series to date, high-dose single-fraction spinal SRS retained an excellent safety profile among long-term survivors (>5 years).

Tumor pseudoprogression of spinal metastasis after radiosurgery: a novel concept and case reports

Radiosurgery for primary and metastatic tumors of the central nervous system is increasing in utility and intensity. Known complications in the brain include radiation necrosis and the well-documented phenomenon of pseudoprogression. Known complications of radiosurgery to spinal column tumors include radiation myelopathy and delayed vertebral compression fractures; however, the concept of pseudoprogression of spinal column tumors has not been previously described. The authors review 2 cases of spinal metastasis treated with stereotactic radiosurgery (SRS) and attempt to define the concept of spine tumor pseudoprogression.

Two patients who had undergone SRS to the spine for metastatic disease presented in early follow-up (3 and 7 weeks) with symptomatic complaints consisting of axial pain, radicular pain, or evidence of cord compression. In both patients, MRI revealed evidence of tumor enlargement. In one patient, the lesion had grown by 9 mm and 7.7 mm in the axial and sagittal planes, respectively. In the other patient, the tumor growth resulted in a 5-mm decrease in spinal canal diameter with epidural compression and right foraminal encroachment. Because of the absence of progressive neurological deficit, myelopathy, mechanical symptomatology of instability, or vertebral compression fracture, the first patient was treated expectantly with a corticosteroid taper and had improvement of symptoms at 1 month and near-total radiographic resolution of the tumor. In the second patient, worsening symptoms suggested a need for surgical intervention to address presumed radiosurgical failure and tumor progression. During surgery, only necrotic tumor cells were observed, without viable tumor. Follow-up imaging over 1 year showed ongoing local control.

To their knowledge, the authors report the first description of pseudoprogression involving spinal column metastasis in the literature and aim to alert the treating physician to this clinical situation. Unlike brain tumor pseudoprogression, spine tumor pseudoprogression is a relatively early posttreatment phenomenon, measured in days to 2 months. The authors believe that the acute inflammatory response associated with tumor necrosis and disruption of the tumor capillary integrity caused by radiotherapy is an important component in the development of pseudoprogression. Future studies will be fundamental in assigning clinical significance, defining the incidence and predictors, and affecting future management of this phenomenon.

Contemporary treatment with radiosurgery for spine metastasis and spinal cord compression in 2015

With the progress of image-guided localization, body immobilization system, and computerized delivery of intensity-modulated radiation delivery, it became possible to perform spine radiosurgery. The next question is how to translate the high technology treatment to the clinical application. Clinical trials have been performed to demonstrate the feasibility of spine radiosurgery and efficacy of the treatment in the setting of spine metastasis, leading to the randomized trials by a cooperative group. Radiosurgery has also demonstrated its efficacy to decompress the spinal cord compression in selected group of patients. The experience indicates that spine radiosurgery has a potential to change the clinical practice in the management of spine metastasis and spinal cord compression.

Update on management of vertebral column tumors

Treatment options for metastatic and primary spinal tumors have expanded in recent years, in part due to the advances made in stereotactic radiosurgery. For metastatic spinal tumors, our institution utilizes the neurologic, oncologic, mechanical, and systemic (NOMS) decision framework, which provides a treatment paradigm based on the neurologic, oncologic, mechanical and systemic status of the patient. Radiosurgery as a supplement to surgical decompression has allowed for less-invasive surgical procedures carrying minimal morbidity while still providing effective local tumor control. Although wide en bloc excision has traditionally been the goal for the treatment of high-grade primary spine tumors, recent studies have shown promise for radiosurgery in providing control in tumors such as chordomas and high-grade sarcomas. Despite advances in radiosurgery, there continues to be limitations in providing effective conformational doses with minimal toxicity to critical structures. One of the ways to circumvent this and supplement external beam radiation is through the use of brachytherapy delivered by radioactive plaque or seeds.

Role of stereotactic body radiotherapy in spinal metastasis and subsequent fracture risk: identifying and treating the at-risk patient

The treatment of spinal metastasis has considerably improved with the advent of stereotactic body radiotherapy. Technological advances have enabled the precise delivery of high-dose radiation that may supplant surgery and standard fractionation postoperative radiation as a treatment for spinal metastasis without cord compression. Unfortunately, the higher biologically equivalent doses conferred by stereotactic body radiotherapy can also result in radiation toxicity, notably myelitis and vertebral body fracture. These are toxicities that the radiation oncologist must be able to anticipate, mitigate and manage. Although myelitis can be prevented largely by instituting dose constraints, it is less clear what the fracture risk of a structurally compromised vertebra is, and what should be done in terms of stabilization and dosimetry to mitigate this risk. This review answers these questions by defining the appropriate patient for stereotactic body radiotherapy, and what dose, fractionation and spinal stabilization should be used for potentially unstable spines.

Separation surgery for spinal metastases: effect of spinal radiosurgery on surgical treatment goals

BACKGROUND

The treatment of epidural spinal cord compression due to metastatic cancer represents an important clinical challenge. The NOMS (neurologic, oncologic, mechanical, and systemic) framework facilitates the determination of the optimal combination of systemic, radiation, and surgical therapies for individual patients. Spinal stereotactic radiosurgery (SRS) is an effective and safe modality for achieving durable control of local disease. Integrating SRS into the postoperative treatment plan allows surgical goals to be modified, thus decreasing the extent of tumor resection required.

METHODS

Separation surgery is indicated for patients with spinal cord compression secondary to solid tumor metastases. During separation surgery, the spinal column is stabilized and the epidural tumor is resected without requiring significant vertebral body resection.

RESULTS

Tumor separation from the spinal cord allows patients to undergo postoperative SRS.

CONCLUSIONS

The combination of separation surgery and high-dose hypofractionated or single-fraction SRS results in high local tumor control at 1 year and is an effective palliative paradigm for this patient population.

Controversial issues in kyphoplasty and vertebroplasty in malignant vertebral fractures

BACKGROUND

Kyphoplasty (KP) and vertebroplasty (VP) have been successfully employed in the treatment of pathological vertebral fractures.

METHODS

A critical review of the medical literature was performed and controversial issues were analyzed.

RESULTS

Evidence supports KP as the treatment of choice to control fracture pain and the possible restoration of sagittal balance, provided that no overt instability or myelopathy is present, the fracture is painful and other pain generators have been excluded, and positive radiological findings are present. Unilateral procedures yield similar results to bilateral ones and should be pursued whenever feasible. Biopsy should be routinely performed and 3 to 4 levels may be augmented in a single operation. Higher cement filling appears to yield better results. Radiotherapy is complementary with KP and VP but must be individualized.

CONCLUSIONS

In cases of painful cancer fractures, if overt instability or myelopathy is not present, unilateral KP should be pursued, whenever feasible, followed by radiotherapy. The technological advances in hardware and biomaterials, as well as combining KP with other modalities, will help ensure a safe and more effective procedure. Address.

Vertebral compression fractures after spine irradiation using conventional fractionation in patients with metastatic colorectal cancer

Purpose

To evaluate the risk of vertebral compression fracture (VCF) after conventional radiotherapy (RT) for colorectal cancer (CRC) with spine metastasis and to identify risk factors for VCF in metastatic and non-metastatic irradiated spines.

Materials and Methods

We retrospectively reviewed 68 spinal segments in 16 patients who received conventional RT between 2009 and 2012. Fracture was defined as a newly developed VCF or progression of an existing fracture. The target volume included all metastatic spinal segments and one additional non-metastatic vertebra adjacent to the tumor-involved spines.

Results

The median follow-up was 7.8 months. Among all 68 spinal segments, there were six fracture events (8.8%) including three new VCFs and three fracture progressions. Observed VCF rates in vertebral segments with prior irradiation or pre-existing compression fracture were 30.0% and 75.0% respectively, compared with 5.2% and 4.7% for segments without prior irradiation or pre-existing compression fracture, respectively (both p < 0.05). The 1-year fracture-free probability was 87.8% (95% CI, 78.2-97.4). On multivariate analysis, prior irradiation (HR, 7.30; 95% CI, 1.31-40.86) and pre-existing compression fracture (HR, 18.45; 95% CI, 3.42-99.52) were independent risk factors for VCF.

Conclusion

The incidence of VCF following conventional RT to the spine is not particularly high, regardless of metastatic tumor involvement. Spines that received irradiation and/or have pre-existing compression fracture before RT have an increased risk of VCF and require close observation.

Management of metastatic cervical spine tumors

The skeletal system is the third most common site of metastases after the lung and liver. Within the skeletal system, the vertebral column is the most common site of metastases, and 8% to 15% of vertebral metastases are in the cervical spine, consisting, anatomically and biomechanically, of the occipitocervical junction, subaxial spine, and cervicothoracic junction. The vertebral body is more commonly affected than the posterior elements. Nonsurgical management techniques include radiation therapy (stereotactic and conventional), bracing, and chemotherapy. Surgical techniques include percutaneous methods, such as vertebroplasty, and palliative methods, such as decompression and stabilization. Surgical approach depends on the location of the tumor and the goals of the surgery. Appropriate patient selection can lead to successful surgical outcomes by restoring spinal stability and improving quality of life.

Cement salvage of instrumentation-associated vertebral fractures

BACKGROUND AND PURPOSE

Spinal instrumentation plays a key role in the treatment of spinal instability in patients with metastatic tumors. Poor bone quality, radiation, and diffuse osseous tumor involvement present significant challenges to spinal stabilization with instrumentation and occasionally result in postinstrumentation compression fractures. Vertebral cement augmentation has been effective in the treatment of painful tumor-related compression fractures. Our objective was to describe cement augmentation options in the treatment of vertebral compression fractures associated with spinal instrumentation in patients with metastatic tumors.

MATERIALS AND METHODS

Patients who underwent percutaneous vertebral cement augmentation in the treatment of instrumentation-associated vertebral compression fractures between 2005 and 2011 were included in the analysis. Only fractures that occurred within the construct or at an adjacent level were included. The change in Visual Analog Scale and need for further surgery were analyzed.

RESULTS

Eleven patients met the inclusion criteria, with 8 tumors located in the thoracic spine and 3 tumors in the lumbar spine. The median time between instrumented surgery and vertebral augmentation was 5 months (1-48 months) and the median follow-up after cement augmentation was 24 months (4-59 months). A total of 22 vertebrae that were either within or immediately adjacent to the surgical instrumentation underwent vertebral augmentation. All patients reported a decrease in their pain scores (mean decrease: 6 Visual Analog Scale points; P < .003). One patient required reoperation after cement augmentation. None of the patients experienced vertebral cement augmentation-related complications.

CONCLUSIONS

Vertebral cement augmentation represents a safe and effective treatment option in patients with recurrent or progressive back pain and instrumentation-associated vertebral compression fractures.

Oligometastasis and oligo-recurrence: more than a mirage

The standard treatment choice for cancer metastasis has been systemic management, including cytotoxic chemotherapy, hormonal manipulation, and targeted therapy. Emerging evidence has shown an oligometastatic state, an intermediate state between limited primary cancer and polymetastatic cancer, in which local therapy for metastatic lesions results in satisfactory survival comparable to non-metastatic disease. We provide a comprehensive introduction of evidence from experimental and clinical studies in favor of the oligometastatic phenotype, we review the efficacy and safety of surgery and stereotactic body radiotherapy in the treatment of oligometastases, and finally, we discuss the way to differentiate the oligometastatic state from polymetastasis.

Safety and efficacy of stereotactic body radiotherapy as primary treatment for vertebral metastases: a multi-institutional analysis

Purpose

To evaluate patient selection criteria, methodology, safety and clinical outcomes of stereotactic body radiotherapy (SBRT) for treatment of vertebral metastases.

Materials and methods

Eight centers from the United States (n = 5), Canada (n = 2) and Germany (n = 1) participated in the retrospective study and analyzed 301 patients with 387 vertebral metastases. No patient had been exposed to prior radiation at the treatment site. All patients were treated with linac-based SBRT using cone-beam CT image-guidance and online correction of set-up errors in six degrees of freedom.

Results

387 spinal metastases were treated and the median follow-up was 11.8 months. The median number of consecutive vertebrae treated in a single volume was one (range, 1-6), and the median total dose was 24 Gy (range 8-60 Gy) in 3 fractions (range 1-20). The median EQD2₁₀ was 38 Gy (range 12-81 Gy). Median overall survival (OS) was 19.5 months and local tumor control (LC) at two years was 83.9%. On multivariate analysis for OS, male sex (p < 0.001; HR = 0.44), performance status <90 (p < 0.001; HR = 0.46), presence of visceral metastases (p = 0.007; HR = 0.50), uncontrolled systemic disease (p = 0.007; HR = 0.45), >1 vertebra treated with SBRT (p = 0.04; HR = 0.62) were correlated with worse outcomes. For LC, an interval between primary diagnosis of cancer and SBRT of ≤30 months (p = 0.01; HR = 0.27) and histology of primary disease (NSCLC, renal cell cancer, melanoma, other) (p = 0.01; HR = 0.21) were correlated with worse LC. Vertebral compression fractures progressed and developed de novo in 4.1% and 3.6%, respectively. Other adverse events were rare and no radiation induced myelopathy reported.

Conclusions

This multi-institutional cohort study reports high rates of efficacy with spine SBRT. At this time the optimal fractionation within high dose practice is unknown.

Current treatment modalities for spinal metastases secondary to thyroid carcinoma

BACKGROUND

The spine is the most common site of bone metastases due to thyroid cancer, which develop in more than 3% of patients with well-differentiated thyroid cancer. Nearly half of patients with bone metastases from thyroid cancer develop vertebral metastases. Spinal metastases are associated with significantly reduced quality of life due to pain, neurological deficit, and increased mortality.

SUMMARY

Treatment options for patients with thyroid spinal metastases include radioiodine therapy, pharmacologic therapy, and surgical treatments, with recent advances in radiosurgery and minimally invasive spinal surgery as well. Therapeutic interventions require a multidisciplinary approach and aim to control pain, preserve or improve neurologic function, optimize local tumor control, and improve quality of life. We have proposed a three-tiered approach to the management and practical algorithms for patients with spinal metastases from thyroid carcinoma.

CONCLUSIONS

The introduction of novel and improved techniques for the treatment of spinal metastases has created the opportunity to significantly improve control of metastatic tumor growth and the quality of life for the patients with spinal metastases from thyroid cancer. In order for these options to be effectively used, a multidisciplinary approach must be applied in the management of the patients with thyroid spinal metastases.

Evaluation of risk factors for vertebral compression fracture after stereotactic radiosurgery in spinal tumor patients

Objective

Stereotactic radiosurgery (SRS) is an emerging treatment modality for malignant spinal tumors. After SRS, some patients suffered from pain aggravation due to development of vertebral compression fracture (VCF). In these cases, surgery should be considered.

Methods

This study consisted of 72 patients who underwent SRS due to spinal tumors. In them, whether post-SRS VCF developed or not was investigated. We retrospectively analyzed their medical records and radiological imaging data. VCF was diagnosed with X-ray and magnetic resonance imaging (MRI). The incidence, time to development and risk factors for VCF were investigated. Age, sex, whole vertebral body involvement rate, vertebral body osteolysis rate, pre-SRS spinal deformity, spinal instability neoplastic score (SINS), spinal canal encroachment, lesion level, and radiation dose were analyzed as potential risk factors. A multi-variate logistic regression model was used for statistical analysis.

Results

In our study population, VCF was observed in 26 patients (36%). The mean time to VCF development was 1.5 months. Using uni-variate analyses, the significant risk factors were pre-SRS spinal deformity, SINS, vertebral body osteolysis rate, and whole vertebral body involvement rate. However, using multi-variate analyses, the only significant risk factor was vertebral body osteolysis rate. The patients whose vertebral body was destroyed by more than 60% showed an 8.4 times higher risk of VCF than those who had vertebral body destruction of less than 60%(p=0.016).

Conclusion

The most significant prognostic factor for post-SRS VCF was vertebral body osteolysis rate, rather than whole vertebral body involvement rate. When more than 60% of the vertebral body was destroyed, the risk of VCF or spinal deformity was high.

Incidence and predictive factors of pain flare after spine stereotactic body radiation therapy: secondary analysis of phase 1/2 trials

PURPOSE/OBJECTIVE(S)

To perform a secondary analysis of institutional prospective spine stereotactic body radiation therapy (SBRT) trials to investigate posttreatment acute pain flare.

METHODS AND MATERIALS

Medical records for enrolled patients were reviewed. Study protocol included baseline and follow-up surveys with pain assessment by Brief Pain Inventory and documentation of pain medications. Patients were considered evaluable for pain flare if clinical note or follow-up survey was completed within 2 weeks of SBRT. Pain flare was defined as a clinical note indicating increased pain at the treated site or survey showing a 2-point increase in worst pain score, a 25% increase in analgesic intake, or the initiation of steroids. Binary logistic regression was used to determine predictive factors for pain flare occurrence.

RESULTS

Of the 210 enrolled patients, 195 (93%) were evaluable for pain flare, including 172 (88%) clinically, 135 (69%) by survey, and 112 (57%) by both methods. Of evaluable patients, 61 (31%) had undergone prior surgery, 57 (29%) had received prior radiation, and 34 (17%) took steroids during treatment, mostly for prior conditions. Pain flare was observed in 44 patients (23%). Median time to pain flare was 5 days (range, 0-20 days) after the start of treatment. On multivariate analysis, the only independent factor associated with pain flare was the number of treatment fractions (odds ratio = 0.66, P=.004). Age, sex, performance status, spine location, number of treated vertebrae, prior radiation, prior surgery, primary tumor histology, baseline pain score, and steroid use were not significant.

CONCLUSIONS

Acute pain flare after spine SBRT is a relatively common event, for which patients should be counseled. Additional study is needed to determine whether prophylactic or symptomatic intervention is preferred.

The incidence and patterns of hardware failure after separation surgery in patients with spinal metastatic tumors

BACKGROUND CONTEXT

Spine metastases occur frequently in patients with cancer. A variety of surgical approaches, including anterior transcavitary, lateral extracavitary, posterolateral, and/or combined techniques are used for spinal cord decompression and restoration of spinal stability. The incidence of symptomatic hardware failure is unknown for the majority of these approaches.

PURPOSE

The purpose of this study was to determine the incidence of symptomatic hardware failure and the associated risk factors in patients with metastatic epidural spinal cord compression (MESCC).

STUDY DESIGN/SETTING

This was a retrospective study.

PATIENT SAMPLE

The current series analyzes a cohort of 318 patients who underwent separation surgery, which involves single-stage posterolateral decompression and posterior segmental instrumentation for MESCC.

OUTCOME MEASURES

The event of interest was hardware failure; the competing event was death resulting from any cause. All patients were monitored for survival analysis. A competing risk analysis was conducted to examine univariately a number of potential risk factors associated with hardware failure, including junctional level, gender, construct length, and the presence or absence of prior chest wall resection.

METHODS

A retrospective analysis and chart review were performed for 318 consecutive patients who underwent posterolateral decompression and posterior screw-rod fixation without supplemental anterior fixation from March 2004 to June 2011 at our institution. The median follow-up time for survivors without hardware failure was 399 days (range, 9-2,828), with a mean operative time of 3 hours. A total of 78% of patients died during the 7-year study period.

RESULTS

Of the 318 patients, nine (2.8%) exhibited signs and symptoms of hardware failure and required revision of the instrumentation. Patients with chest wall resection and those with initial construct length greater than six contiguous spinal levels exhibited a statistically significantly higher risk of symptomatic hardware failure than their counterparts. We observed a trend toward an increased risk of failure in women compared with men (p=.09).

CONCLUSIONS

The incidence of hardware failure is low in patients with MESCC who undergo posterolateral decompression and posterior screw-rod instrumentation. Moreover, the short operative time and low morbidity profile associated with this approach make it a reliable and acceptable method for the surgical treatment of MESCC. Patients with constructs spanning six or more levels or those with prior chest wall resection are at higher risk for instrumentation failure.

The role of stereotactic body radiotherapy and stereotactic radiosurgery in the re-irradiation of metastatic spinal tumors

Stereotactic body radiotherapy (SBRT) and stereotactic radiosurgery (SRS) are advanced radiotherapy delivery techniques that allow for the delivery of high-dose per fraction radiation. Advances in imaging technology and intensity modulation have allowed SRS and SBRT to be used for the treatment of tumors in close proximity to the spinal cord and cauda equina, in particular spinal metastases. While the initial treatment of spinal metastases is often conventional palliative radiotherapy, treatment failure is not uncommon, and conventional re-irradiation may not be feasible due to spinal cord tolerance. SBRT and SRS have emerged as important techniques for the treatment of spinal metastases in the proximity of previously irradiated spinal cord. Here we review the current data on the use of SBRT and SRS spinal re-irradiation, and future directions for these important treatment modalities.

The integration of radiosurgery for the treatment of patients with metastatic spine diseases

Significant evidence emerging in the spinal oncology literature recommends radiosurgery as a primary modality of treatment of spinal metastasis. Improvements in the methods of delivering radiation have increased the ability to provide a higher and more exacting dose of radiation to a tumor bed than previously. Using treatment-planning software, radiation is contoured around a specific lesion with the intent of administering a tumoricidal dose. Combined with a minimally invasive, tumor-load reducing surgery, this advanced form of radiation therapy can provide better local control of the tumor compared with conventional external beam radiation.

Bone health in breast cancer patients: a comprehensive statement by CECOG/SAKK Intergroup

Bone is the most common site of distant metastases in breast cancer that can cause severe and debilitating skeletal related events (SRE) including hypercalcemia of malignancy, pathologic fracture, spinal cord compression and the need for palliative radiation therapy or surgery to the bone. SRE are associated with substantial pain and morbidity leading to frequent hospitalization, impaired quality of life and poor prognosis. The past 25 years of research on the pathophysiology of bone metastases led to the development of highly effective treatment options to delay or prevent osseous metastases and SRE. Management of bone metastases has become an integral part of cancer treatment requiring expertise of multidisciplinary teams of medical and radiation oncologists, surgeons and radiologists in order to find an optimal treatment for each individual patient. A group of international breast cancer experts attended a Skeletal Care Academy Meeting in November 2012 in Istanbul and discussed current preventive measures and treatment options of SRE, which are summarized in this evidence-based consensus for qualified decision- making in clinical practice.

Stereotactic radiosurgery for brain and spine metastases

Metastases to the brain and spine are common and difficult to treat. Stereotactic radiosurgery (SRS) is a non-invasive treatment option for some individuals, and may obviate the need for open surgery and/or whole brain radiotherapy. Over the past decade there has been an increased number of patients undergoing SRS for the treatment of metastatic disease, and multiple published studies show favourable results in terms of local disease control. We review the available literature pertaining to the application of SRS for the treatment of brain and spine metastases, together with its limitations and outcomes.

Acute exposure to high dose γ-radiation results in transient activation of bone lining cells

The present studies investigated the cellular mechanisms for the detrimental effects of high dose whole body γ-irradiation on bone. In addition, radioadaptation and bone marrow transplantation were assessed as interventions to mitigate the skeletal complications of irradiation. Increased trabecular thickness and separation and reduced cancellous bone volume fraction, connectivity density, and trabecular number were detected in proximal tibia and lumbar vertebra 14days following γ-irradiation with 6Gy. To establish the cellular mechanism for the architectural changes, vertebrae were analyzed by histomorphometry 1, 3, and 14days following irradiation. Marrow cell density decreased within 1day (67% reduction, p<0.0001), reached a minimum value after 3days (86% reduction, p<0.0001), and partially rebounded by 14days (30% reduction, p=0.0025) following irradiation. In contrast, osteoblast-lined bone perimeter was increased by 290% (1day, p=0.04), 1230% (3days, p<0.0001), and 530% (14days, p=0.003), respectively. There was a strong association between radiation-induced marrow cell death and activation of bone lining cells to express the osteoblast phenotype (Pearson correlation -0.85, p<0.0001). An increase (p=0.004) in osteoclast-lined bone perimeter was also detected with irradiation. A priming dose of γ-radiation (0.5mGy), previously shown to reduce mortality, had minimal effect on the cellular responses to radiation and did not prevent detrimental changes in bone architecture. Bone marrow transplantation normalized marrow cell density, bone turnover, and most indices of bone architecture following irradiation. In summary, radiation-induced death of marrow cells is associated with 1) a transient increase in bone formation due, at least in part, to activation of bone lining cells, and 2) an increase in bone resorption due to increased osteoclast perimeter. Bone marrow transplantation is effective in mitigating the detrimental effects of acute exposure to high dose whole body γ-radiation on bone turnover.

Vertebral compression fracture after stereotactic body radiotherapy for spinal metastases

The use of stereotactic body radiotherapy for metastatic spinal tumours is increasing. Serious adverse events for this treatment include vertebral compression fracture (VCF) and radiation myelopathy. Although VCF is a fairly low-risk adverse event (approximately 5% risk) after conventional radiotherapy, crude risk estimates for VCF after spinal SBRT range from 11% to 39%. In this Review, we summarise the evidence and predictive factors for VCF induced by spinal SBRT, review the pathophysiology of VCF in the metastatic spine, and discuss strategies used to prevent and manage this potentially disabling complication.

Vertebral compression fracture after spine stereotactic body radiotherapy: a multi-institutional analysis with a focus on radiation dose and the spinal instability neoplastic score

PURPOSE

Vertebral compression fracture (VCF) is increasingly recognized as an adverse event after spine stereotactic body radiotherapy (SBRT). We report a multi-institutional study aimed at clarifying the risk and predictive factors associated with VCF.

PATIENTS AND METHODS

A total of 252 patients with 410 spinal segments treated with SBRT were included. The primary outcome was the development of VCF (a new VCF or progression of a baseline VCF). In addition to various patient-, treatment-, and tumor-specific factors, the Spinal Instability Neoplastic Scoring (SINS) system was applied to determine predictive value.

RESULTS

The median follow-up was 11.5 months (range, 0.03 to 113 months). The median and mean overall survival rates were 16 and 26 months, respectively. We observed 57 fractures (57 of 410, 14%), with 47% (27 of 57) new fractures and 53% (30 of 57) fracture progression. The median time to VCF was 2.46 months (range, 0.03 to 43.01 months), and 65% occurred within the first 4 months. The 1- and 2-year cumulative incidences of fracture were 12.35% and 13.49%, respectively. Multivariable analysis identified dose per fraction (greatest risk for ≥ 24 Gy v 20 to 23 Gy v ≤ 19 Gy), in addition to three of the six original SINS criteria: baseline VCF, lytic tumor, and spinal deformity, as significant predictors of VCF.

CONCLUSION

Caution must be observed when treating with ≥ 20 Gy/fraction, in particular, for patients with lytic tumor, spinal misalignment, and a baseline VCF. Frequent short-term follow-up is required, as nearly two thirds of all VCF occurred within the first 4 months. We also conclude that SINS may have utility in predicting patients at high risk of SBRT-induced VCF.

Outcomes and toxicities of stereotactic body radiation therapy for non-spine bone oligometastases

PURPOSE

Stereotactic body radiation therapy (SBRT) is being applied more widely for oligometastatic disease. This technique is now being used for non-spine bony metastases in addition to liver, spine, and lung. However, there are few studies examining the toxicity and outcomes of SBRT for non-spine bone metastases.

METHODS AND MATERIALS

Between 2008 and 2012, 74 subjects with oligometastatic non-spine bony metastases of varying histologies were treated at the Mayo Clinic with SBRT. A total of 85 non-spine bony sites were treated. Median local control, overall survival, and progression-free survival were described. Acute toxicity (defined as toxicity <90 days) and late toxicity (defined as toxicity ≥90 days) were reported and graded as per standardized Common Toxicity Criteria for Adverse Events 4.0 criteria.

RESULTS

The median age of patients treated was 60 years. The most common histology was prostate cancer (31%) and most patients had fewer than 3 sites of disease at the time of simulation (64%). Most of the non-spine bony sites lay within the pelvis (65%). Dose and fractionation varied but the most common prescription was 24 Gy/1 fraction. Local recurrence occurred in 7 patients with a median time to failure of 2.8 months. Local control was 91.8% at 1 year. With a median follow-up of 7.6 months, median SBRT specific overall survival and progression-free survival were 9.3 months and 9.7 months, respectively. Eighteen patients developed acute toxicity (mostly grade 1 and 2 fatigue and acute pain flare); 9 patients developed grade 1-2 late toxicities. Two patients developed pathologic fractures but both were asymptomatic. There were no late grade 3 or 4 toxicities.

CONCLUSIONS

Stereotactic body radiation therapy is a feasible and tolerable treatment for non-spine bony metastases. Longer follow-up will be needed to accurately determine late effects.

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.

Developments in stereotactic ablative radiotherapy for the treatment of early-stage lung cancer

SUMMARY Stereotactic ablative radiotherapy (SABR), also known as stereotactic body radiation therapy, has emerged as an effective treatment for inoperable early-stage non-small-cell lung cancer. SABR differs from conventional radiotherapy by virtue of its tight spatial tolerances and use of oligofractionated radiation. The modern technique is characterized by management of tumor motion, image guidance before each fraction and specialized radiation delivery techniques. The result is a highly conformal target dose with a sharp gradient that spares normal tissues with great accuracy. This enables delivery of very potent (ablative) doses, causing more rapid and durable responses than traditional radiation therapy treatment regimens can achieve. The established techniques, new developments and ongoing questions related to SABR for early-stage non-small-cell lung cancer are reviewed herein.

Radiation-induced vertebral compression fracture following spine stereotactic radiosurgery: clinicopathological correlation

Spine stereotactic radiosurgery (SRS) is increasingly being used to treat metastatic spinal tumors. As the experience matures, high rates of vertebral compression fracture (VCF) are being observed. What is unknown is the mechanism of action; it has been postulated but not confirmed that radiation itself is a contributing factor. This case report describes 2 patients who were treated with spine SRS who subsequently developed signal changes on MRI consistent with tumor progression and VCF; however, biopsy confirmed a diagnosis of radiation-induced necrosis in 1 patient and fibrosis in the other. Radionecrosis is a rare and serious side effect of high-dose radiation therapy and represents a diagnostic challenge, as the authors have learned from years of experience with brain SRS. These cases highlight the issues in the new era of spine SRS with respect to relying on imaging alone as a means of determining true tumor progression. In those scenarios in which it is unclear based on imaging if true tumor progression has occurred, the authors recommend biopsy to rule out radiation-induced effects within the bone prior to initiating salvage therapies.

Serious complications associated with stereotactic ablative radiotherapy and strategies to mitigate the risk

The clinical applications of stereotactic body radiotherapy or stereotactic ablative radiotherapy (SABR) for the treatment of primary and metastatic tumours of different organ sites have been expanding rapidly in the recent decade. SABR requires advanced technology in radiotherapy planning and image guidance to deliver a highly conformal ablative dose precisely to targets (or tumours) in the body. Although this treatment modality has shown promising results with regard to tumour control, some serious complications have been observed and reported. In order to achieve a favourable therapeutic ratio, strategies to mitigate the risk of complications must be in place. This overview will summarise the reported serious complications caused by SABR and strategies to mitigate the risk will be discussed.

Interview: Current state of brain and spine radiosurgery and future applications

Arjun Sahgal works in the field of high-precision stereotactic radiation to the brain and spine. After training at the University of Toronto (ON, Canada) in radiation oncology, he completed a fellowship at the University of California, San Francisco (CA, USA) in brain and spine radiosurgery with Professor David Larson. Since then, he has been recognized as a national and international clinical expert and research leader in radiosurgery. His main focus is on developing spine stereotactic body radiotherapy (SBRT), also known as spine radiosurgery, as an effective therapy for patients with spinal tumors. Research achievements include publishing spinal cord tolerance guidelines for spine SBRT as part of an international multi-institutional effort. This work elucidated safe dose limits for the spinal cord specific to spine SBRT, and was the first of its kind. He has developed the spine SBRT program for the University of Toronto and is conducting the first Phase II clinical study on spine SBRT for metastases in Canada. He has also recently written national guidelines on behalf of the Canadian Association of Radiation Oncology (CARO) for the practice of spine, lung and liver SBRT, and continues to lead national and international multi-institutional groups dedicated to spine and brain radiosurgery research.

Stereotactic body radiotherapy for oligometastases

The management of metastatic solid tumours has historically focused on systemic treatment given with palliative intent. However, radical surgical treatment of oligometastases is now common practice in some settings. The development of stereotactic body radiotherapy (SBRT), building on improvements in delivery achieved by intensity-modulated and image-guided radiotherapy, now allows delivery of ablative doses of radiation to extracranial sites. Many non-randomised studies have shown that SBRT for oligometastases is safe and effective, with local control rates of about 80%. Importantly, these studies also suggest that the natural history of the disease is changing, with 2-5 year progression-free survival of about 20%. Although complete cure might be possible in a few patients with oligometastases, the aim of SBRT in this setting is to achieve local control and delay progression, and thereby also postpone the need for further treatment. We review published work showing that SBRT offers durable local control and the potential for progression-free survival in non-liver, non-lung oligometastatic disease at a range of sites. However, to test whether SBRT really does improve progression-free survival, randomised trials will be essential.