Patient outcomes and tumor control in single-fraction versus hypofractionated stereotactic body radiation therapy for spinal metastases

Efficacy and safety of SBRT for spine metastases: A systematic review and meta-analysis for preparation of an ESTRO practice guideline

BACKGROUND AND PURPOSE

Advances in characterizing cancer biology and the growing availability of novel targeted agents and immune therapeutics have significantly changed the prognosis of many patients with metastatic disease. Palliative radiotherapy needs to adapt to these developments. In this study, we summarize the available evidence for stereotactic body radiotherapy (SBRT) in the treatment of spinal metastases.

MATERIALS AND METHODS

A systematic review and meta-analysis was performed using PRISMA methodology, including publications from January 2005 to September 2021, with the exception of the randomized phase III trial RTOG-0631 which was added in April 2023. Re-irradiation was excluded. For meta-analysis, a random-effects model was used to pool the data. Heterogeneity was assessed with the I2-test, assuming substantial and considerable as I2 > 50 % and I2 > 75 %, respectively. A p-value < 0.05 was considered statistically significant.

RESULTS

A total of 69 studies assessing the outcomes of 7236 metastases in 5736 patients were analyzed. SBRT for spine metastases showed high efficacy, with a pooled overall pain response rate of 83 % (95 % confidence interval [CI] 68 %-94 %), pooled complete pain response of 36 % (95 % CI: 20 %-53 %), and 1-year local control rate of 94 % (95 % CI: 86 %-99 %), although with high levels of heterogeneity among studies (I2 = 93 %, I2 = 86 %, and 86 %, respectively). Furthermore, SBRT was safe, with a pooled vertebral fracture rate of 9 % (95 % CI: 4 %-16 %), pooled radiation induced myelopathy rate of 0 % (95 % CI 0-2 %), and pooled pain flare rate of 6 % (95 % CI: 3 %-17 %), although with mixed levels of heterogeneity among the studies (I2 = 92 %, I2 = 0 %, and 95 %, respectively). Only 1.7 % of vertebral fractures required surgical stabilization.

CONCLUSION

Spine SBRT is characterized by a favorable efficacy and safety profile, providing durable results for pain control and disease control, which is particularly relevant for oligometastatic patients.

A Cancer Care Ontario Consensus-Based Organizational Guideline for the Planning and Delivery of Spine Stereotactic Body Radiation Therapy Treatment in Ontario

The proposed recommendations are primarily based on the consensus opinion and in-field experience of the Ontario Health/Cancer Care Ontario stereotactic body radiation therapy (SBRT) for Spine Metastasis Guideline Development Group and published literature when available. Primary consideration was given to the perceived benefits for patients and the small likelihood of harm arising from recommendation implementation. Apart from the magnetic resonance imaging (MRI) follow-up strategy, all evidence was considered indirect and was provided by the working group in conjunction with their collective expertise in the field of SBRT. The application of an SBRT program requires a multidisciplinary team consisting of a radiation oncologist, spine surgeon, neuroradiologist, medical physicist, medical dosimetrist, and radiation therapist. In Canada, linear accelerators are the most used treatment delivery units and should follow technology-specific quality assurance procedures. Immobilization technique is location dependant. Treatment planning MRI sequences should be acquired no more than 14 days from the date of treatment. In the case of epidural disease, simulation MRI should be completed no more than 7 days from the date of treatment. After treatment, patients should be followed with routine clinical visits every 3 months for the first year, every 3 to 6 months during years 2 and 3, and every 4 to 6 months thereafter. The recommendations enclosed provide a framework for the minimum requirements for a cancer center in Ontario, Canada to offer SBRT for spine metastases.