Spinal reirradiation after short-course RT for metastatic spinal cord compression

External Beam Radiation Therapy for Palliation of Symptomatic Bone Metastases: An ASTRO Clinical Practice Guideline

PURPOSE

This guideline provides evidence-based recommendations for palliative external beam radiation therapy (RT) in symptomatic bone metastases.

METHODS

The ASTRO convened a task force to address 5 key questions regarding palliative RT in symptomatic bone metastases. Based on a systematic review by the Agency for Health Research and Quality, recommendations using predefined consensus-building methodology were established; evidence quality and recommendation strength were also assessed.

RESULTS

For palliative RT for symptomatic bone metastases, RT is recommended for managing pain from bone metastases and spine metastases with or without spinal cord or cauda equina compression. Regarding other modalities with RT, for patients with spine metastases causing spinal cord or cauda equina compression, surgery and postoperative RT are conditionally recommended over RT alone. Furthermore, dexamethasone is recommended for spine metastases with spinal cord or cauda equina compression. Patients with nonspine bone metastases requiring surgery are recommended postoperative RT. Symptomatic bone metastases treated with conventional RT are recommended 800 cGy in 1 fraction (800 cGy/1 fx), 2000 cGy/5 fx, 2400 cGy/6 fx, or 3000 cGy/10 fx. Spinal cord or cauda equina compression in patients who are ineligible for surgery and receiving conventional RT are recommended 800 cGy/1 fx, 1600 cGy/2 fx, 2000 cGy/5 fx, or 3000 cGy/10 fx. Symptomatic bone metastases in selected patients with good performance status without surgery or neurologic symptoms/signs are conditionally recommended stereotactic body RT over conventional palliative RT. Spine bone metastases reirradiated with conventional RT are recommended 800 cGy/1 fx, 2000 cGy/5 fx, 2400 cGy/6 fx, or 2000 cGy/8 fx; nonspine bone metastases reirradiated with conventional RT are recommended 800 cGy/1 fx, 2000 cGy/5 fx, or 2400 cGy/6 fx. Determination of an optimal RT approach/regimen requires whole person assessment, including prognosis, previous RT dose if applicable, risks to normal tissues, quality of life, cost implications, and patient goals and values. Relatedly, for patient-centered optimization of treatment-related toxicities and quality of life, shared decision making is recommended.

CONCLUSIONS

Based on published data, the ASTRO task force's recommendations inform best clinical practices on palliative RT for symptomatic bone metastases.

Risk Factors for Radiotherapy Failure in the Treatment of Spinal Metastases

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To build a predictive model for risk factors for failure of radiation therapy, hypothesizing a higher SINS would correlate with failure.

METHODS

Patients with spinal metastasis being treated with radiation at a tertiary care academic center between September 2014 and October 2018 were identified. The primary outcome measure was radiation therapy failure as defined by persistent pain, need for re-irradiation, or surgical intervention. Risk factors were primary tumor type, Karnofsky and ECOG scores, time to treatment, biologically effective dose (BED) calculations using α/β ratio = 10, and radiation modality. A logistic regression was used to construct a prediction model for radiation therapy failure.

RESULTS

One hundred and seventy patients were included. Median follow up was 91.5 days. Forty-three patients failed radiation therapy. Of those patients, 10 required repeat radiation and 7 underwent surgery. Thirty-six patients reported no pain relief, including some that required re-irradiation and surgery. Total SINS score for those who failed reduction therapy was <7 for 27 patients (62.8%), between 7-12 for 14 patients (32.6%), and >12 for 2 patients (4.6%). In the final prediction model, BED (OR .451 for BED > 43 compared to BED ≤ 43; P = .174), Karnofksy score (OR .736 for every 10 unit increase in Karnofksy score; P = .008), and gender (OR 2.147 for male compared to female; P = .053) are associated with risk of radiation failure (AUC .695). A statistically significant association between SINS score and radiation therapy failure was not found.

CONCLUSIONS

In the multivariable model, BED ≤ 43, lower Karnofksy score, and male gender are predictive for radiotherapy failure. SINS score was among the candidate risk factors included in multivariable model building procedure, but it was not selected in the final model.

LEVEL OF EVIDENCE

Prognostic level III.

Spinal Reirradiation-Mediated Myelopathy: A Systematic Review and Meta-Analysis

Reirradiation of the spine is carried out in 42% of patients who do not respond to treatment or have recurrent pain. However, there are few studies and data on the effect of reirradiation of the spine and the occurrence of acute and chronic side-effects caused by reirradiation, such as myelopathy, in these patients. This meta-analysis aimed to determine the safe dose in terms of biological effective dose (BED), cumulative dose and dose interval between BED1 and BED2 to decrease or prevent myelopathy and pain control in patients undergoing radiation therapy in the spinal cord. A search was carried out using EMBASE, MEDLINE, PUBMED, Google Scholar, Cochrane Collaboration library electronic databases, Magiran, and SID from 2000 to 2022 to recognise qualified studies. In total, 17 primary studies were applied to estimate the pooled effect size. The random effects model showed that the pooled BED in the first stage, the BED in the second stage and the cumulative BED1 and BED2 were estimated at 77.63, 58.35 and 115.34 Gy, respectively. Studies reported on dose interval. The results of a random effects model showed that the pooled interval was estimated at 13.86 months. The meta-analysis revealed that using appropriate BED1 and/or BED2 in a safe interval between the first and second phases of treatment can have an influential role in preventing or reducing the effects of myelopathy and regional control pain in spinal reirradiation.

Efficacy and toxicity of primary re-irradiation for malignant spinal cord compression based on radiobiological modelling: a phase II clinical trial

BACKGROUND

The efficacy and safety of primary re-irradiation for MSCC are not known. Our aim was to establish the efficacy and safety of biologically effective dose-based re-irradiation.

METHODS

Patients presenting with MSCC at a previously irradiated spine segment, and not proceeding with surgical decompression, were eligible. A 3 Gray per fraction experimental schedule (minimum 18 Gy/6 fractions, maximum 30 Gy/10 fractions) was used, delivering a maximum cumulative spinal dose of 100 Gy2 if the interval since the last radiotherapy was within 6 months, or 130 Gy2 if longer. The primary outcome was a change in mobility from week 1 to week 5 post-treatment, as assessed by the Tomita score. The RTOG SOMA score was used to screen for spinal toxicity, and an MRI performed to assess for radiation-induced myelopathy (RIM).

RESULTS

Twenty-two patients were enroled, of whom eleven were evaluable for the primary outcome. Nine of eleven (81.8%) had stable or improved Tomita scores at 5 weeks. One of eight (12.5%) evaluable for late toxicity developed RIM.

CONCLUSIONS

Re-irradiation is an efficacious treatment for MSCC. There is a risk of RIM with a cumulative dose of 120 Gy2.

CLINICAL TRIAL REGISTRATION

Cancer Trials Ireland (ICORG 07-11); NCT00974168.

European Society for Radiotherapy and Oncology and European Organisation for Research and Treatment of Cancer consensus on re-irradiation: definition, reporting, and clinical decision making

Re-irradiation can be considered for local recurrence or new tumours adjacent to a previously irradiated site to achieve durable local control for patients with cancer who have otherwise few therapeutic options. With the use of new radiotherapy techniques, which allow for conformal treatment plans, image guidance, and short fractionation schemes, the use of re-irradiation for different sites is increasing in clinical settings. Yet, prospective evidence on re-irradiation is scarce and our understanding of the underlying radiobiology is poor. Our consensus on re-irradiation aims to assist in re-irradiation decision making, and to standardise the classification of different forms of re-irradiation and reporting. The consensus has been endorsed by the European Society for Radiotherapy and Oncology and the European Organisation for Research and Treatment of Cancer. The use of this classification in daily clinical practice and research will facilitate accurate understanding of the clinical implications of re-irradiation and allow for cross-study comparisons. Data gathered in a uniform manner could be used in the future to make recommendations for re-irradiation on the basis of clinical evidence. The consensus document is based on an adapted Delphi process and a systematic review of the literature was done according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA).

Radiotherapy of bone metastases

We present the update of the recommendations of the French society of oncological radiotherapy on bone metastases. This is a common treatment in the management of patients with cancer. It is a relatively simple treatment with proven efficacy in reducing pain or managing spinal cord compression. More complex treatments by stereotaxis can be proposed for oligometastatic patients or in case of reirradiation. In this context, increased vigilance should be given to the risks to the spinal cord.

Stereotactic Ablative Radiotherapy for the Management of Spinal Metastases: A Review

Importance

Rising cancer incidence combined with improvements in systemic and local therapies extending life expectancy are translating into more patients with spinal metastases. This makes the multidisciplinary management of spinal metastases and development of new therapies increasingly important. Spinal metastases may cause significant pain and reduced quality of life and lead to permanent neurological disability if compression of the spinal cord and/or nerve root occurs. Until recently, treatments for spinal metastases were not optimal and provided temporary local control and pain relief. Spinal stereotactic ablative radiotherapy (SABR) is an effective approach associated with an improved therapeutic ratio, with evolving clinical application.

Objective

To review the literature of spinal SABR for spinal metastases, discuss a multidisciplinary approach to appropriate patient selection and technical considerations, and summarize current efforts to combine spinal SABR with systemic therapies.

Evidence Review

The MEDLINE database was searched to identify articles reporting on spinal SABR to September 30, 2018. Articles including clinical trials, prospective and retrospective studies, systematic reviews, and consensus recommendations were selected for relevance to multidisciplinary management of spinal metastases.

Results

Fifty-nine unique publications with 5655 patients who underwent SABR for spinal metastases were included. Four comprehensive frameworks for patient selection were discussed. Spinal SABR was associated with 1-year local control rates of approximately 80% to 90% in the de novo setting, greater than 80% in the postoperative setting, and greater than 65% in the reirradiation setting. The most commonly discussed adverse effect was development of a vertebral compression fracture with variable rates, most commonly reported as approximately 10% to 15%. High-level data on the combination of SABR with modern therapies are still lacking. At present, 19 clinical trials are ongoing, mainly focusing on combined modality therapies, radiotherapy prescription dose, and oligometastic disease.

Conclusions and Relevance

These findings suggest that spinal SABR may be an effective treatment option for well-selected patients with spinal metastases, achieving high rates of local tumor control with moderate rates of adverse effects. Optimal management should include review by a multidisciplinary care team.

Management of recurrent or progressive spinal metastases: reirradiation techniques and surgical principles

With the growing incidence of new cases and the increasing prevalence of patients living longer with spine metastasis, a methodological approach to the management of patients with recurrent or progressive disease is increasing in relevance and importance in clinical practice. As a result, disease management has evolved in these patients using advanced surgical and radiotherapy technologies. Five key goals in the management of patients with spine metastases include providing pain relief, controlling metastatic disease at the treated site, improving neurologic deficits, maintaining or improving functional status, and minimizing further mechanical instability. The focus of this review is on advanced reirradiation techniques, given that the majority of patients will be treated with upfront conventional radiotherapy and further treatment on progression is often limited by the cumulative tolerance of nearby organs at risk. This review will also discuss novel surgical approaches such as separation surgery, minimally invasive percutaneous instrumentation, and laser interstitial thermal therapy, which is increasingly being coupled with spine reirradiation to maximize outcomes in this patient population. Lastly, given the complexities of managing recurrent spinal disease, this review emphasizes the importance of multidisciplinary care from neurosurgery, radiation oncology, medical oncology, neuro-oncology, rehabilitation medicine, and palliative care.

Diffusion-weighted MRI and 18F-FDG PET correlation with immunity in early radiotherapy response in BNL hepatocellular carcinoma mouse model: timeline validation

PURPOSE

Imaging probes/biomarkers that are correlated with molecular or microenvironmental alterations in tumors have been used not only in diagnosing cancer but also in assessing the efficacy of cancer treatment. We evaluated the early response of hepatocellular carcinoma (HCC) to radiation treatment using T2-weighted magnetic resonance imaging (MRI), diffusion-weighted (DW) MRI, and ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET).

METHODS

Orthotopic HCC tumors were established in the right liver lobe of Balb/c mice. Mice were longitudinally scanned using T2-weighted/DW MRI and ¹⁸F-FDG PET 1 day before and on days 1, 3, 6, 9 and 13 after irradiation with 15 Gy to the right liver lobe to determine tumor size, apparent diffusion coefficient (ADC) value, and maximum standardized uptake value. Immunohistochemical (IHC) staining was performed to validate the tumor microenvironment.

RESULTS

Irradiation markedly retarded tumor growth in the orthotopic HCC model and led to increaes in ADC values as early as on day 1 after irradiation. Irradiation also resulted in increases in ¹⁸F-FDG uptake on day 1 that were sustained until the end of the observation period. IHC staining revealed a decrease in the number of proliferative cells and a continuous macrophage influx into irradiated tumors, which dramatically altered the tumor microenvironment. Lastly, in vitro coculture of HCC cells and macrophages led to interaction between the cells and enhanced the cellular uptake of ¹⁸F-FDG.

CONCLUSION

ADC values and ¹⁸F-FDG uptake measured using DW MRI and ¹⁸F-FDG PET serve as potential biomarkers for early assessment of HCC tumor responses to radiation therapy.

Diabetes increases the risk of serious adverse events after re-irradiation of the spine

INTRODUCTION

In this study we investigate the risk of radiation-induced serious adverse event of the spine in a large cohort of consecutive retreated patients with palliative radiotherapy (RT) for metastatic cancer in the spine.

METHODS AND MATERIALS

From 2010 to 2014, 2387 patients received spinal irradiation with a palliative intent for metastatic spinal cord compression at our institution. The patients were reviewed for prior RT and 220 patients had received re-irradiation of the spine. Clinical and treatment data were obtained from the patients' records and the RT planning system.

RESULTS

Patients had metastatic disease from breast, prostate, lung, hematological or other cancers (22.7%, 21.8%, 21.4%, 3.2% and 30.9%, respectively). Median follow-up was 99 days. Median cumulative EQD2 was 57.6 Gy₂; range: 20.0-90.0 Gy. Spinal events related to re-irradiation were observed in fourteen patients; six patients were diagnosed with radiation-induced myelopathy (RIM) and nine patients with radiation-induced vertebral fracture (RIF). In a multivariate analysis, diabetes was related to increased risk of toxicity (HR = 7.9; P = 0.003).

CONCLUSION

The incidence of RIM and RIF (6 and 9 out of 220 patients, respectively) was low in our cohort of re-irradiated patients. Patients with diabetes had a higher risk of adverse events which should be considered before re-irradiation of the spine.

Personalized Radiation Therapy in Cancer Pain Management

The majority of advanced cancer patients suffer from pain, which severely deteriorates their quality of life. Apart from analgesics, bisphosphonates, and invasive methods of analgesic treatment (e.g., intraspinal and epidural analgesics or neurolytic blockades), radiation therapy plays an important role in pain alleviation. It is delivered to a growing primary tumour, lymph nodes, or distant metastatic sites, producing pain of various intensity. Currently, different regiments of radiation therapy methods and techniques and various radiation dose fractionations are incorporated into the clinical practice. These include palliative radiation therapy, conventional external beam radiation therapy, as well as modern techniques of intensity modulated radiation therapy, volumetrically modulated arch therapy, stereotactic radiosurgery or stereotactic body radiation therapy, and brachytherapy or radionuclide treatment (e.g., radium-223, strontium-89 for multiple painful osseous metastases). The review describes the possibilities and effectiveness of individual patient-tailored conventional and innovative radiation therapy approaches aiming at pain relief in cancer patients.

Epidural and intramedullary spinal metastasis: clinical features and role of fractionated radiotherapy

Metastases involving the spinal epidural space and cord parenchyma are major sources of neurological impairment and decreased quality of life in cancer patients. Herein we review the clinical manifestations, pathophysiology, importance of early diagnosis and initiation of treatment, and role of fractionated radiotherapy of these disorders.

Overall survival after reirradiation of spinal metastases - independent validation of predictive models

BACKGROUND

It is unknown if survival prediction tools (SPTs) sufficiently predict survival in patients who undergo palliative reirradiation of spinal metastases. We therefore set out to clarify if SPTs can predict survival in this patient population.

METHODS

We retrospectively analyzed spinal reirradiations performed (n = 58, 52 patients, 44 included in analysis). SPTs for patients with spinal metastases were identified and compared to a general palliative score and to a dedicated SPT to estimate prognosis in palliative reirradiation independent of site (SPT-Nieder).

RESULTS

Consistently in all tests, SPT-Nieder showed best predictive performance as compared to other tools. Items associated with survival were general condition (KPS), liver metastases, and steroid use. Other factors like primary tumor site, pleural effusion, and bone metastases were not correlated with survival. We adapted an own score to the data which performed comparable to SPT-Nieder but avoids the pleural effusion item. Both scores showed good performance in identifying long-term survivors with late recurrences.

CONCLUSIONS

Survival prediction in case of spinal reirradiation is possible with sufficient predictive separation. Applying SPTs in case of reirradiation helps to identify patients with good life expectancy who might benefit from dose escalation or longer treatment courses.

Assessment of national practice for palliative radiation therapy for bone metastases suggests marked underutilization of single-fraction regimens in the United States

PURPOSE

To characterize temporal trends in the application of various bone metastasis fractionations within the United States during the past decade, using the National Cancer Data Base; the primary aim was to determine whether clinical practice in the United States has changed over time to reflect the published randomized evidence and the growing movement for value-based treatment decisions.

PATIENTS AND METHODS

The National Cancer Data Base was used to identify patients treated to osseous metastases from breast, prostate, and lung cancer. Utilization of single-fraction versus multiple-fraction radiation therapy was compared according to demographic, disease-related, and health care system details.

RESULTS

We included 24,992 patients treated during the period 2005-2011 for bone metastases. Among patients treated to non-spinal/vertebral sites (n=9011), 4.7% received 8 Gy in 1 fraction, whereas 95.3% received multiple-fraction treatment. Over time the proportion of patients receiving a single fraction of 8 Gy increased (from 3.4% in 2005 to 7.5% in 2011). Numerous independent predictors of single-fraction treatment were identified, including older age, farther travel distance for treatment, academic treatment facility, and non-private health insurance (P<.05).

CONCLUSIONS

Single-fraction palliative radiation therapy regimens are significantly underutilized in current practice in the United States. Further efforts are needed to address this issue, such that evidence-based and cost-conscious care becomes more commonplace.

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.

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.

Re-irradiation of spinal column metastases by IMRT: impact of setup errors on the dose distribution

BACKGROUND

This study investigates the impact of an automated image guided patient setup correction on the dose distribution for ten patients with in-field IMRT re-irradiation of vertebral metastases.

METHODS

10 patients with spinal column metastases who had previously been treated with 3D-conformal radiotherapy (3D-CRT) were simulated to have an in-field recurrence. IMRT plans were generated for treatment of the vertebrae sparing the spinal cord. The dose distributions were compared for a patient setup based on skin marks only and a Cone Beam CT (CBCT) based setup with translational and rotational couch corrections using an automatic robotic image guided couch top (Elekta - HexaPOD™ IGuide® - system). The biological equivalent dose (BED) was calculated to evaluate and rank the effects of the automatic setup correction for the dose distribution of CTV and spinal cord.

RESULTS

The mean absolute value (± standard deviation) over all patients and fractions of the translational error is 6.1 mm (±4 mm) and 2.7° (±1.1 mm) for the rotational error. The dose coverage of the 95% isodose for the CTV is considerable decreased for the uncorrected table setup. This is associated with an increasing of the spinal cord dose above the tolerance dose.

CONCLUSIONS

An automatic image guided table correction ensures the delivery of accurate dose distribution and reduces the risk of radiation induced myelopathy.

[Advances in radiation oncology for metastatic bone disease]

INTRODUCTION

Irradiation of bone metastases primarily aims at alleviating pain, preventing fracture in the short term. The higher doses and more conformal dose distribution achievable while saving healthy tissue with new irradiation techniques have induced a paradigm shift in the management of bone metastases in a growing number of clinical situations.

MATERIALS AND METHODS

A search of the English and French literature was conducted using the keywords: bone metastases, radiotherapy, interventional radiology, vertebroplasty, radiofrequency, chemoembolization. RESULTS-DISCUSSION: Stereotactic irradiation yields pain relief rates greater than 90% in Phase I/II and retrospective studies. IMRT (static, rotational, helical) and stereotactic irradiation yield local control rates of 75-90% at 2 years. Some situations previously evaluated as palliative are currently treated more aggressively with optimized radiation sometimes combined modality interventional radiology.

CONCLUSION

A recommendation can only be made for stereotactic irradiation in vertebral oligometastases or reirradiation. In the absence of a sufficient level of evidence, the increasing use of conformal irradiation techniques can only reflect the daily practice and the patient benefit while integrating economic logic care. The impact of these aggressive approaches on survival remains to be formally demonstrated by interventional prospective studies or observatories including quality of life items and minimal 2-year follow-up.

Intraoperative and percutaneous iridium-192 high-dose-rate brachytherapy for previously irradiated lesions of the spine

PURPOSE

Advances in stereotactic radiosurgery have improved local control of spine metastases, but local failure is still a problem and repeat irradiation is limited by normal tissue tolerance. A novel high-dose-rate (HDR) brachytherapy technique has been developed to treat these previously irradiated lesions.

METHODS AND MATERIALS

Five patients with progressive disease at previously irradiated sites in the spine who were not amenable to further external beam radiation were treated. Catheters were placed intraoperatively in 2 patients and percutaneously implanted in 3 patients with image-guided techniques. Conformal plans were generated to deliver dose to target tissues and spare critical structures. Patients received single-fraction treatment using HDR iridium-192 brachytherapy.

RESULTS

Median dose was 14 Gy (range, 12-18 Gy) with a median gross total volume D90 of 75% (range, 31-94%); spinal cord/cauda equina dose constraints were met. At a median followup of 9 months, no local progression of disease has been observed. Four patients had reduction in pain 1-4 weeks after treatment. No brachytherapy-related complications have been observed.

CONCLUSIONS

Intraoperative and percutaneous iridium-192 HDR spine brachytherapy techniques were not associated with complications or acute toxicity. There has been no local progression at treated sites, and most patients experienced reduction in cancer-related pain.

Spinal cord disease in patients with cancer

PURPOSE OF REVIEW

Spinal cord disease is not uncommon in patients with systemic cancer. Most cases are due to epidural tumor metastases with resulting cord compression, although intramedullary spinal cord metastases, radiation myelopathy, and myelopathic complications of chemotherapy must be considered.

RECENT FINDINGS

Techniques for surgical decompression of the spinal cord in patients with epidural tumor have improved significantly over the past decade. Several studies have demonstrated improved neurologic outcome in a subset of patients with epidural spinal cord compression treated surgically.

SUMMARY

This article outlines the clinical features, radiographic findings, and differential diagnosis of spinal cord disease in patients with cancer and describes the therapeutic approach to these patients. Early identification and treatment of patients with epidural spinal cord compression is critical to maintaining neurologic function and preserving quality of life.

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

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

Impact of dose on local failure rates after image-guided reirradiation of recurrent paraspinal metastases

PURPOSE

To examine the impact of dose on local failure (LF) rates in the re-treatment of recurrent paraspinal metastases with image-guided intensity-modulated radiotherapy (IG-IMRT).

METHODS AND MATERIALS

The records of patients with in-field recurrence after previous spine radiation (median dose, 30 Gy) who received salvage IG-IMRT with either five 4-Gy (20-Gy group, n = 42) or five 6-Gy (30-Gy group, n = 55) daily fractions between January 2003 and August 2008 were reviewed. Institutional practice was 20 Gy before April 2006, when it changed to 30 Gy. A total of 47 cases (48%) were treated adjuvantly, after surgery to decompress epidural disease. LF after IG-IMRT was defined radiographically.

RESULTS

The median follow-up was 12.1 months (range, 0.2-63.6 months). The 1-year cumulative incidences of LF after 20 Gy and 30 Gy IG-IMRT were 45% and 26%, respectively (p = 0.04). Of all treatment characteristics examined (20-Gy vs. 30-Gy dose group, dose to 95% of the planned and gross target volume, tumor size, histology, receipt of surgery, and interval between first and second radiation), only dose group had a significant impact on actuarial LF incidence (p = 0.04; unadjusted HR, 0.51; 95% CI, 0.27-0.96). There was no incidence of myelopathy.

CONCLUSIONS

A significant decrease in LF after IG-IMRT with five 6-Gy fractions compared with five 4-Gy fractions was observed without increased risk of myelopathy. Until prospective data comparing stereotactic hypofractionated and single-fraction regimens become available, when reirradiating recurrent paraspinal metastases with IG-IMRT, administration of five 6-Gy daily fractions is reasonable.

The role of radiotherapy for metastatic epidural spinal cord compression

Radiotherapy alone is the most common treatment for metastatic epidural spinal cord compression (MESCC). Decompressive surgery followed by radiotherapy is generally indicated only in 10-15% of MESCC cases. Chemotherapy has an unclear role and may be considered for selected patients with hematological or germ-cell malignancies. If radiotherapy alone is given, it is important to select the appropriate regimen. Similar functional outcomes can be achieved with short-course radiotherapy regimens and longer-course radiotherapy regimens. Longer-course radiotherapy is associated with better local control of MESCC than short-course radiotherapy. Patients with a more favorable survival prognosis (expected survival of ≥6 months) should receive longer-course radiotherapy, as they may live long enough to develop a recurrence of MESCC. Patients with an expected survival of <6 months should be considered for short-course radiotherapy. A recurrence of MESCC in the previously irradiated region after short-course radiotherapy may be treated with another short-course of radiotherapy. After primary administration of longer-course radiotherapy, decompressive surgery should be performed if indicated. Alternatively, re-irradiation can be performed using high-precision techniques to reduce the cumulative dose received by the spinal cord. Larger prospective trials are required to better define the appropriate treatment for the individual patient.

Metastatic spinal cord compression: review of the evidence for a radiotherapy dose fractionation schedule

Metastatic spinal cord compression is a frequent medical emergency, and the most common treatment offered is radiotherapy. The routine treatment prescription for spinal cord compression in the UK is 20 Gy in five daily fractions delivered over 1 week. Here, we evaluate the evidence base for the radiotherapy dose for spinal cord compression. Evidence from the four prospective studies conducted so far and retrospective studies does not support a uniform dose of 20 Gy for all patients with spinal cord compression. Available evidence suggests that the radiotherapy dose should be tailored to the individual patient, depending on the subtype of the tumour, the extent of metastatic disease and expected survival. A risk stratification for the optimum dose prescription for patients with spinal cord compression is recommended.

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

STUDY DESIGN

Systematic literature review.

OBJECTIVE

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

METHODS

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

RESEARCH QUESTIONS

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

RESULTS

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

CONCLUSION

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

Further Radiobiologic Modeling of Palliative Radiotherapy: Use of Virtual Trials

PURPOSE

To study duration of response in palliative radiotherapy in a population of tumors.

METHODS AND MATERIALS

Models of dynamic changes in cell number with time were used to develop a function for the remission time (T(rem)) after palliative radiotherapy: [See Equation], where BED is the biologically effective dose, t(1) the duration of symptoms (i.e., the time between the onset of symptoms and the initiation of radiotherapy), K the daily BED repopulation equivalent, alpha the linear radiosensitivity parameter in the linear-quadratic model, and z the tumor regression rate.

RESULTS

Simulations of clinical trials show marked variations in remission statistics depending on the tumor characteristics and are highly compatible with the results of clinical trials. Dose escalation produces both a higher proportion and extended duration of remissions, especially in tumors with high alpha/beta ratios and K values, but the predicted dose responses of acute and late side effects show that caution is necessary. The prospect of using particle beam therapy to reduce normal tissue radiation exposures or using hypoxic sensitizers to improve the tumor cell kill might significantly improve the results of palliative radiotherapy in carefully selected patients and could also be used for safer palliative re-treatments in patients with the potential for prolonged survival. The effect of tumor heterogeneity in determining palliative responses probably exceeds that in radical radiotherapy; as few as 100 patients in each treatment arm produce statistically unreliable results.

CONCLUSIONS

Virtual trials of palliative radiotherapy can be useful to test the effects of competing schedules and better determine future strategies, including improved design of clinical trials as well as combinations of radiotherapy with other anticancer modalities.

Fractionated, single-port radiotherapy delays paresis in a metastatic spinal tumor model in rats

Object

Spinal column metastatic disease affects thousands of cancer patients every year. Radiation therapy frequently represents the primary treatment for this condition. Despite the enormous clinical impact of spinal column metastatic disease, the literature currently lacks an accurate animal model for testing the efficacy of irradiation on spinal column metastases.

Methods

After anesthesia was induced, female Fischer 344 rats underwent a transabdominal approach to the ventral vertebral body (VB) of L-6. A 2- to 3-mm-diameter bur hole was drilled for the implantation of a section of CRL-1666 breast adenocarcinoma. After the animals had recovered from the surgery, they underwent fractionated, single-port radiotherapy beginning on postoperative Day 7. Each group of animals underwent five daily fractions of radiation treatment. Group I animals received a total dose of 10 Gy in 200-cGy daily fractions, Group II animals received a total dose of 20 Gy in 400-cGy daily fractions, and Group III animals received a total dose of 30 Gy in 600-cGy daily fractions. A control group of rats with implanted VB lesions did not receive radiation. To test the effects of radiation toxicity alone, additional rats without implanted tumors received radiation treatments in the same fractions as the rats with tumors. Hindlimb function in all rats was rated before and after radiation treatment using the Basso-Beattie-Bresnahan locomotor rating scale. Histological analysis of spinal cord and vertebral column sections was performed after each animal's death.

Results

Functional assessments demonstrated a statistically significant delay in the onset of paresis between the three treatment groups and the control group (tumor implanted but no radiotherapy). The rats in the three treatment groups, however, did not exhibit any significant differences related to hindlimb function. A dose-dependent relationship was found for the percentage of animals who had become paralyzed at the time of death, with all members of the control group and no members of the 30-Gy group exhibiting paralysis. The results of this study do not indicate any overall survival benefit for any level of radiation dose.

Conclusions

These findings demonstrate the efficacy of focal spinal irradiation in delaying the onset of paralysis in a rat metastatic spine tumor model, but without a clear survival benefit. Because of the dose-related toxicity observed in the rats treated with 30 Gy, this effect was most profound for the 20-Gy group. This finding parallels the observed clinical course of spinal column metastatic disease in humans and provides a basis for the future comparison of novel local and systemic treatments to augment the observed effects of focal irradiation.