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

Area of Science:

• Radiation Oncology
• Medical Physics
• Oncology

Background:

• Stereotactic body radiotherapy (SBRT) is a key treatment for spinal metastases.
• A standard 2-fraction SBRT protocol exists, but alternatives are needed for complex cases.
• This study evaluates a novel 30 Gy in 4 fractions SBRT protocol.

Purpose of the Study:

• To assess the safety and efficacy of a 30 Gy in 4 fractions SBRT protocol for spinal metastases.
• To report imaging-based outcomes, including local failure and vertebral compression fractures (VCF).
• To identify predictors of VCF in patients treated with this protocol.

Main Methods:

• Retrospective review of patients treated with 30 Gy/4 fractions SBRT from 2010-2021.
• Analysis of magnetic resonance imaging (MRI) for VCF and local failure.
• Multivariate analysis to identify risk factors for VCF.

Main Results:

• 245 segments in 116 patients were analyzed. Median age was 64.
• Two-year cumulative incidence of local failure was 16% and VCF was 11.2%.
• Increased VCF risk was associated with age ≥68, clinical target volume (CTV) ≥72 cc, and no prior surgery. No radiation-induced myelopathy was observed.

Conclusions:

• The 30 Gy in 4 fractions SBRT protocol is safe and effective for spinal metastases, including high-risk patients.
• Lower VCF risk in previously stabilized segments suggests benefit from multimodal approaches.
• This protocol is particularly beneficial for complex metastases with large CTV volumes (≥72 cc).