30 Gy in 4 Stereotactic Body Radiotherapy Fractions for Complex Spinal Metastases: Mature Outcomes Supporting This Novel Regimen

Advanced Radiotherapy Technologies in Spine Tumors: What the Surgeon Needs to Know

STUDY DESIGN

Narrative review of existing literature.

OBJECTIVES

Significant technological advancements in radiotherapy planning and delivery have enabled new radiotherapy techniques for the management of spine tumors. The objective of this study was to provide a comprehensive summary of these treatment techniques for practicing spine surgeons.

METHODS

A narrative review of the existing literature on stereotactic body radiation therapy (SBRT) and particle beam therapy (PBT) for the treatment of spine tumors was performed. The characteristics, implementation and evidence supporting these strategies in the management of primary spinal neoplasms were summarized.

RESULTS

The clinical effectiveness of SBRT for the control and symptom palliation of metastatic spinal tumors are well demonstrated in multiple clinical trials. Risks such as fracture, radiculopathy and plexopathy exist after spine SBRT, necessitating an individualized approach in a well experienced multidisciplinary setting. SBRT should be considered a key component of a well-rounded treatment plan for metastatic spine tumors in combination with surgery, vertebral augmentation, and drug therapy, where indicated, to achieve optimal patient outcomes. Additionally, PBT and SBRT are also leading to promising results for primary spine tumors, though comparative effectiveness studies and prospective clinical trials are required to establish these modalities more formally as alternatives to conventionally fractionated photon radiotherapy.

CONCLUSIONS

SBRT and PBT are emerging as effective and well tolerated treatment options for primary and metastatic spine tumors. Additional investigation is needed to personalize these treatment options and further strengthen these approaches as key components in a multidisciplinary approach to the management of spinal neoplasms.

A case series and review of stereotactic body radiation therapy for contiguous multilevel spine metastases

PURPOSE

A majority of published series report on stereotactic body radiation therapy (SBRT) for 1-2 contiguous vertebral levels due to concerns regarding setup accuracy and radiation toxicity. This study evaluates patients with metastases spanning ≥ 3 contiguous levels treated with SBRT and augments its findings with a review of other studies investigating multilevel spine SBRT.

METHODS

Analysis of a prospectively collected database of 49 patients with 55 metastases spanning ≥ 3 contiguous vertebral levels treated with SBRT at a single institution (2002-2023) was performed. Outcomes identified included local failure (LF), pain response, overall survival, and toxicity. The median single-fraction prescription dose was 15 Gy (range: 8-18); multifractionated treatment utilized prescription doses of 18-30 Gy in 2-5 fractions.

RESULTS

Median follow-up was 7 months (range: 1-103). The 6-month, 1-year, and 2-year cumulative incidence rates of LF were 7%, 11%, and 11%, respectively. No prognostic factors were associated with LF. Pain was reported to improve or remain stable for 49 lesions (89%). Ten adverse radiation events (18%) were identified; pain flare (5%), dermatitis (4%), and vertebral compression fracture (VCF, 9%). The 3-month, 6-month, and 1-year cumulative incidence rates of VCF were 4%, 7%, and 7%, respectively. No instances of esophageal toxicity or myelopathy were observed.

CONCLUSIONS

This study of multilevel SBRT is one of the largest to investigate outcomes in this challenging clinical scenario. Spine SBRT confers low rates of LF and toxicity for patients with multilevel disease, which was previously considered a relative contraindication. Spine SBRT may be considered in this patient population instead of low-dose palliative RT.

Spine Stereotactic Body Radiation Therapy in Geriatric Patients: Implications of Age and Dose on Iatrogenic Vertebral Compression Fracture Risk

PURPOSE

Stereotactic body radiation therapy (SBRT) is an effective treatment for spinal metastases; however, outcomes specific to a geriatric population have not been described. This study aims to investigate the efficacy and safety of spine SBRT, in particular the rate of iatrogenic vertebral compression fracture (VCF), in patients aged 70 and older.

PATIENTS AND METHODS

From a prospectively maintained single-institutional database of 976 patients and 2407 spinal segments treated with SBRT for vertebral metastases between 2008 and 2021, all patients aged 70 or above were retrospectively reviewed. The primary outcome is the risk of VCF. Secondary outcomes included magnetic resonance imaging-based local failure and overall survival.

RESULTS

A total of 252 consecutive patients with 580 spinal segments treated with spine SBRT were reviewed. The median age was 75.8 (range: 70-90.3) years and the median (interquartile range) follow-up duration was 16.9 (6.4-41.3) months. The median overall survival of the entire cohort was 20.3 months and the 2-year local failure rate was 14.3%. The cumulative risk of VCF at 12 and 24 months were 8.4% and 12.3%, respectively. Significant predictors of VCF on multivariable analyses included greater biologically equivalent dose, baseline fracture, and increasing age. In particular, the 2-year VCF rate and median time to VCF were 30.3% and 3.4 months for those 86 and older, compared with 11.2% and 12.8 months for those younger than 86, respectively (P = .0011).

CONCLUSION AND RELEVANCE

Spine SBRT should be considered in a geriatric population; however, for those 86 and older, we suggest caution due to the significant risk of VCF.

Shifting the Landscape of Spine and Non-Spine Bone Metastases: A Review of Stereotactic Body Radiotherapy

ABSTRACT

Both spine and nonspine bone metastases are frequent sites of spread from solid organ malignancies. As bone metastases frequently cause significant morbidity for patients, it is critical to offer a treatment that can achieve rapid and durable symptomatic relief and local control, without being associated with serious risks of toxicity. Conventional palliative radiation therapy has a key treatment component in the multidisciplinary management of these patients; however, over the past decade, it has evolved to routinely deliver high biologically effective doses with precision in the form of stereotactic body radiation therapy. This change in paradigm is a result of the shifting landscape in cancer care, such that short-term pain relief is no longer the sole therapeutic aim for selected patients, and durable symptom relief and local tumor control are the goals. This review discusses the randomized prospective evidence, ongoing trials, approach to surveillance imaging, and treatment delivery for stereotactic body radiation therapy, to both spine and nonspine bone metastases, with a specific section on sacral metastases.

Stereotactic Body Radiation Therapy for Sacral Metastases: Deviation From Recommended Target Volume Delineation Increases the Risk of Local Failure

PURPOSE

Although spine stereotactic body radiation therapy (SBRT) is considered a standard of care in the mobile spine, mature evidence reporting outcomes specific to sacral metastases is lacking. Furthermore, there is a need to validate the existing sacral SBRT international consensus contouring guidelines to define the optimal contouring approach. We report mature rates of local failure (LF), adverse events, and the effect of contouring deviations in the largest experience to date specific to sacrum SBRT.

METHODS AND MATERIALS

Consecutive patients who underwent sacral SBRT from 2010 to 2021 were retrospectively reviewed. The primary endpoint was magnetic resonance imaging-based LF with a focus on adherence to target volume contouring recommendations. Secondary endpoints included vertebral compression fracture and neural toxicity.

RESULTS

Of the 215 sacrum segments treated in 112 patients, most received 30 Gy/4 fractions (51%), 24 Gy/2 fractions (31%), or 30 Gy/5 fractions (10%). Sixteen percent of segments were nonadherent to the consensus guideline with a more restricted target volume (undercontoured). The median follow-up was 21.4 months (range, 1.5-116.9 months). The cumulative incidence of LF at 1 and 2 years was 18.4% and 23.1%, respectively. In those with guideline adherent versus nonadherent contours, the LF rate at 1 year was 15.1% versus 31.4% and at 2 years 18.8% versus 40.0% (hazard ratio [HR], 2.5; 95% CI, 1.4-4.6; P = .003), respectively. On multivariable analysis, guideline nonadherence (HR, 2.4; 95% CI, 1.3-4.7; P = .008), radioresistant histology (HR, 2.4; 95% CI, 1.4-4.1; P < .001), and extraosseous extension (HR, 2.5; 95% CI, 1.3-4.7; P = .005) predicted for an increased risk of LF. The cumulative incidence of vertebral compression fracture was 7.1% at 1 year and 12.3% at 2 years. Seven patients (6.3%) developed peripheral nerve toxicity, of whom 4 had been previously radiated.

CONCLUSIONS

Sacral SBRT is associated with high efficacy rates and an acceptable toxicity profile. Adhering to consensus guidelines for target volume delineation is recommended to reduce the risk of LF.

Optimizing Clinical Implementation of Hypofractionation: Comprehensive Evidence Synthesis and Practical Guidelines for Low- and Middle-Income Settings

The global cancer burden, especially in low- and middle-income countries (LMICs), worsens existing disparities, amplified by the rising costs of advanced treatments. The shortage of radiation therapy (RT) services is a significant issue in LMICs. Extended conventional treatment regimens pose significant challenges, especially in resource-limited settings. Hypofractionated radiotherapy (HRT) and ultra-hypofractionated/stereotactic body radiation therapy (SBRT) offer promising alternatives by shortening treatment durations. This approach optimizes the utilization of radiotherapy machines, making them more effective in meeting the growing demand for cancer care. Adopting HRT/SBRT holds significant potential, especially in LMICs. This review provides the latest clinical evidence and guideline recommendations for the application of HRT/SBRT in the treatment of breast, prostate, and lung cancers. It emphasizes the critical importance of rigorous training, technology, stringent quality assurance, and safety protocols to ensure precise and secure treatments. Additionally, it addresses practical considerations for implementing these treatments in LMICs, highlighting the need for comprehensive support and collaboration to enhance patient access to advanced cancer care.

Determining patients with spinal metastases suitable for surgical intervention: A cost-effective analysis

BACKGROUND

Both nonoperative and operative treatments for spinal metastasis are expensive interventions. Patients' expected 3-month survival is believed to be a key factor to determine the most suitable treatment. However, to the best of our knowledge, no previous study lends support to the hypothesis. We sought to determine the cost-effectiveness of operative and nonoperative interventions, stratified by patients' predicted probability of 3-month survival.

METHODS

A Markov model with four defined health states was used to estimate the quality-adjusted life years (QALYs) and costs for operative intervention with postoperative radiotherapy and radiotherapy alone (palliative low-dose external beam radiotherapy) of spine metastases. Transition probabilities for the model, including the risks of mortality and functional deterioration, were obtained from secondary and our institutional data. Willingness to pay thresholds were prespecified at $100,000 and $150,000. The analyses were censored after 5-year simulation from a health system perspective and discounted outcomes at 3% per year. Sensitivity analyses were conducted to test the robustness of the study design.

RESULTS

The incremental cost-effectiveness ratios were $140,907 per QALY for patients with a 3-month survival probability >50%, $3,178,510 per QALY for patients with a 3-month survival probability <50%, and $168,385 per QALY for patients with independent ambulatory and 3-month survival probability >50%.

CONCLUSIONS

This study emphasizes the need to choose patients carefully and estimate preoperative survival for those with spinal metastases. In addition to reaffirming previous research regarding the influence of ambulatory status on cost-effectiveness, our study goes a step further by highlighting that operative intervention with postoperative radiotherapy could be more cost-effective than radiotherapy alone for patients with a better survival outlook. Accurate survival prediction tools and larger future studies could offer more detailed insights for clinical decisions.