The impact of decompression with instrumentation on local failure following spine stereotactic radiosurgery

Spinal tumours: recommendations of the Polish Society of Spine Surgery, the Polish Society of Oncology, the Polish Society of Neurosurgeons, the Polish Society of Oncologic Surgery, the Polish Society of Oncologic Radiotherapy, and the Polish Society of Orthopaedics and Traumatology

PURPOSE

The purpose of these recommendations is to spread the available evidence for evaluating and managing spinal tumours among clinicians who encounter such entities.

METHODS

The recommendations were developed by members of the Development Recommendations Group representing seven stakeholder scientific societies and organizations of specialists involved in various forms of care for patients with spinal tumours in Poland. The recommendations are based on data yielded from systematic reviews of the literature identified through electronic database searches. The strength of the recommendations was graded according to the North American Spine Society's grades of recommendation for summaries or reviews of studies.

RESULTS

The recommendation group developed 89 level A-C recommendations and a supplementary list of institutions able to manage primary malignant spinal tumours, namely, spinal sarcomas, at the expert level. This list, further called an appendix, helps clinicians who encounter spinal tumours refer patients with suspected spinal sarcoma or chordoma for pathological diagnosis, surgery and radiosurgery. The list constitutes a basis of the network of expertise for the management of primary malignant spinal tumours and should be understood as a communication network of specialists involved in the care of primary spinal malignancies.

CONCLUSION

The developed recommendations together with the national network of expertise should optimize the management of patients with spinal tumours, especially rare malignancies, and optimize their referral and allocation within the Polish national health service system.

Long-term outcomes of spinal SBRT. Is it important to select the treatment time?

PURPOSE

SBRT (stereotactic body radiation therapy) is widely used as a curative treatment in tumoral lesions and has become a fundamental tool for the treatment of spine metastasis. In this study, we present survival and toxicity outcomes of spine SBRT after a 2-year follow-up.

METHODS/PATIENTS

Data from spine SBRT treatments performed at our institution between March 2012 and February 2020 was collected. Medical records, including demographic, primary tumor, and treatment characteristics were reviewed. Patient follow-up included clinical evaluation, imaging, and blood tests. Toxicity was recorded according to CTCAE v4.0.

RESULTS

We analyzed 73 consecutive spine SBRT treatments in 60 patients. 39.7% of the cases had primary breast cancer and 23.3% had prostate cancer. Most cases (87.7%) were treated with a single SBRT fraction of 16 Gy. Median follow-up was 26.1 months (range 1.7-78.6), and 1- and 2-year overall survival (OS) rates were 96.9% and 84.2%, respectively. Local control (LC) rates at 1- and 2-years were 76.3% and 70.6%, respectively. Multivariate analysis identified histology as a prognostic factor for both OS and LC. Patients who underwent spine SBRT 6 months after the spinal lesion diagnosis had LC at 2 years of 88%, vs 61.7% for those who underwent SBRT before this period. No grade III or higher toxicity was reported. The vertebral compression fracture (VCF) rate was 4.1%.

CONCLUSION

Spine SBRT at our institution showed a 2-year LC of 70.6%, without G3 toxicities. Delaying SBRT at least 6 months to administer systemic treatment was related to an improvement in local control.

Characteristics and Predictors of Radiographic Local Failure in Patients With Spinal Metastases Treated With Palliative Conventional Radiation Therapy

Purpose

Although local control is an important issue for longer-term survivors of spinal metastases treated with conventional external beam radiation therapy (EBRT), the literature on radiographic local failure (LF) in these patients is sparse. To inform clinical decision-making, we evaluated rates, consequences, and predictors of radiographic LF in patients with spinal metastases managed with palliative conventional EBRT alone.

Methods and Materials

We retrospectively reviewed 296 patients with spinal metastases who received palliative EBRT at a single institution (2006-2013). Radiographic LF was defined as radiologic progression within the treatment field, with death considered a competing risk. Kaplan-Meier, cumulative incidence, and Cox regression analyses determined overall survival estimates, LF rates, and predictors of LF, respectively.

Results

There were 182 patients with follow-up computed tomography or magnetic resonance imaging; median overall survival for these patients was 7.7 months. Patients received a median of 30 Gy in 10 fractions to a median of 4 vertebral bodies. Overall, 74 of 182 patients (40.7%) experienced LF. The 6-, 12-, and 18-month LF rates were 26.5%, 33.1%, and 36.5%, respectively, while corresponding rates of death were 24.3%, 38.1%, and 45.9%. Median time to LF was 3.8 months. Of those with LF, 51.4% had new compression fractures, 39.2% were admitted for pain control, and 35.1% received reirradiation; median time from radiation therapy (RT) to each of these events was 3.0, 5.7, and 9.2 months, respectively. Independent predictors of LF included single-fraction RT (8 Gy) (hazard ratio [HR], 2.592; 95% confidence interval [CI], 1.437-4.675; P = .002), lung histology (HR, 3.568; 95% CI, 1.532-8.309; P = .003), and kidney histology (HR, 4.937; 95% CI, 1.529-15.935; P = .008).

Conclusions

Patients experienced a >30% rate of radiographic LF by 1 year after EBRT. Single-fraction RT and lung or kidney histology predicted LF. Given the high rates of LF for patients with favorable prognosis, assessing the risk of death versus LF is important for clinical decision-making.

Stereotactic Body Radiation Therapy for Spinal Metastases: Tumor Control Probability Analyses and Recommended Reporting Standards

PURPOSE

We sought to investigate the tumor control probability (TCP) of spinal metastases treated with stereotactic body radiation therapy (SBRT) in 1 to 5 fractions.

METHODS AND MATERIALS

PubMed-indexed articles from 1995 to 2018 were eligible for data extraction if they contained SBRT dosimetric details correlated with actuarial 2-year local tumor control rates. Logistic dose-response models of collected data were compared in terms of physical dose and 3-fraction equivalent dose.

RESULTS

Data were extracted from 24 articles with 2619 spinal metastases. Physical dose TCP modeling of 2-year local tumor control from the single-fraction data were compared with data from 2 to 5 fractions, resulting in an estimated α/β = 6 Gy, and this was used to pool data. Acknowledging the uncertainty intrinsic to the data extraction and modeling process, the 90% TCP corresponded to 20 Gy in 1 fraction, 28 Gy in 2 fractions, 33 Gy in 3 fractions, and (with extrapolation) 40 Gy in 5 fractions. The estimated TCP for common fractionation schemes was 82% at 18 Gy, 90% for 20 Gy, and 96% for 24 Gy in a single fraction, 82% for 24 Gy in 2 fractions, and 78% for 27 Gy in 3 fractions.

CONCLUSIONS

Spinal SBRT with the most common fractionation schemes yields 2-year estimates of local control of 82% to 96%. Given the heterogeneity in the tumor control estimates extracted from the literature, with variability in reporting of dosimetry data and the definition of and statistical methods of reporting tumor control, care should be taken interpreting the resultant model-based estimates. Depending on the clinical intent, the improved TCP with higher dose regimens should be weighed against the potential risks for greater toxicity. We encourage future reports to provide full dosimetric data correlated with tumor local control to allow future efforts of modeling pooled data.

Local Control and Toxicity of Multilevel Spine Stereotactic Body Radiotherapy

BACKGROUND

Spine stereotactic body radiotherapy (sSBRT) is commonly limited to 1 or 2 vertebral levels given a paucity of efficacy and toxicity data when more than 2 levels are treated.

OBJECTIVE

To prove our hypothesis that multilevel sSBRT could provide similar rates of local control (LC) (primary endpoint) and toxicity as single-level treatment using the same clinical target, planning target, and planning organ-at-risk volumes.

METHODS

We analyzed consecutive cases of sSBRT treated from 2013 to 2017. Time-to-event outcomes for single-level and multilevel cases were compared using mixed effect Cox models and differences in toxicity rates were evaluated using linear mixed effect models. All models incorporate a patient-level random intercept to account for any within-patient correlation across cases.

RESULTS

There were 101 single-level and 84 multilevel sSBRT cases (2-7 continuous vertebral levels). One-year LC was 95% vs 85%, respectively. After adjusting for baseline covariates, dose delivered, and accounting for within-patient correlation, there was no significant difference in time to local failure (hazard ratio, HR 1.79 [0.59-5.4]; P = .30). Pain improved in 83.5% of the 139 initially symptomatic tumors. There were no significant differences in grade 2+ acute or late toxicities between single-level and multilevel sSBRT.

CONCLUSION

With rigorous patient immobilization, quality assurance, and image guidance, multilevel sSBRT provides high rates of LC, similar to single-level treatment, without need for larger planning volume margins. Efforts to improve prognostication and case selection for multilevel sSBRT are warranted to ensure that the benefits of improved LC over palliative radiation are justified.

Evolving Role of Stereotactic Body Radiation Therapy in the Management of Spine Metastases: Defining Dose and Dose Constraints

When treating solid tumor spine metastases, stereotactic high-dose-per-fraction radiation, given in a single fraction or in a hypofractionated approach, has proved to be a highly effective and safe therapeutic option for any tumor histology, in the setting of de novo therapy, as salvage treatment of local progression after previous radiation, and in the postoperative setting. There are variations in practice based on the clinical presentation, goals of therapy, as well as institutional preferences. As a biologically potent therapy, a thoughtful and careful attention to detail with patient selection, treatment planning, and delivery is crucial for treatment success.

Efficacy and safety of different fractions in stereotactic body radiotherapy for spinal metastases: A systematic review

BACKGROUND

In the treatment of spinal metastases, stereotactic body radiotherapy (SBRT) delivers precise, high-dose radiation to the target region while sparing the spinal cord. A range of doses and fractions had been reported; however, the optimal prescribed scheme remains unclear.

METHODS

Two reviewers performed independent literature searches of the PubMed, EMBASE, Cochrane Database, and Web of Science databases. Articles were divided into one to five fractions groups. The Methodological Index for Non-randomized Studies (MINORS) was used to assess the quality of studies. Local control (LC) and overall survival (OS) were presented for the included studies and a pooled value was calculated by the weighted average.

RESULTS

The 38 included studies comprised 3,754 patients with 4,731 lesions. The average 1-year LCs for the one to five fractions were 92.7%, 84.6%, 86.8%, 82.6%, and 80.6%, respectively. The average 1-year OS for the one to five fractions were 53.0%, 70.4%, 60.1%, 48%, and 80%, respectively. The 24 Gy/single fraction scheme had a higher 1-year LC (98.1%) than those of 24 Gy/two fractions (85.4%), 27 Gy/three fractions (84.9%), and 24 Gy/three fractions (89.0%). The incidence of vertebral compression fracture was 10.3%, with 10.7% in the single-fraction group and 10.1% in the multi-fraction group. The incidence of radiation-induced myelopathy was 0.19%; three and two patients were treated with single-fraction and multi-fraction SBRT, respectively. The incidence of radiculopathy was 0.30% and all but one patient were treated with multi-fraction SBRT.

CONCLUSIONS

SBRT provided satisfactory efficacy and acceptable safety for spinal metastases. Single-fraction SBRT demonstrated a higher local control rate than those of the other factions, especially the 24 Gy dose. The risk of vertebral compression fracture (VCF) was slightly higher in single-fraction SBRT and more patients developed radiculopathy after multi-fraction SBRT.

Radiographic Rate and Clinical Impact of Pseudarthrosis in Spine Radiosurgery for Metastatic Spinal Disease

Purpose

Pseudarthrosis within the spine tumor population is increased from perioperative radiation and complex stabilization for invasive and recurrent pathology. We report the radiographic and clinical rates of pseudarthrosis following multiple courses of instrumented fusion and perioperative stereotactic radiosurgery (SRS).

Methods

We performed a single institution review of 418 patients treated with non-isocentric SRS for spine between October 2002 and January 2013, identifying those with spinal instrumentation and greater than six months of follow-up. Surgical history, radiation planning, and radiographic outcomes were documented.

Results

Eleven patients who met criteria for inclusion underwent 21 sessions of spinal SRS and 16 instrumented operations. Radiographic follow-up was 48.9 months; 3/11 (27%) were with radiographic hardware failure, and one (9%) separate case ultimately warranted externalization due to tumor recurrence. SRS was administered to treat progression of disease in 12/21 (57%) procedures, and residual lesions in 7/11 (64%) procedures. Following first and second SRS, 8/11 (73%) and 2/7 (29%) patients were with symptomatic improvement, respectively.

Conclusion

Risk of pseudarthrosis following SRS for patients with oncologic spinal lesions will become increasingly apparent with the optimized management of and survival from spinal pathologies. We highlight how the need for local control outpaces the risk of instrumentation failure.