Stereotactic Body Radiation Therapy (SBRT)
Stereotactic Body Radiation Therapy (SBRT) is a highly precise, non-invasive radiation treatment technique that delivers high doses of radiation to well-defined tumor targets in a single or few fractions while minimizing exposure to surrounding healthy tissues. 1, 2, 3
Definition and Key Characteristics
- SBRT is an advanced form of external beam radiotherapy that:
- Delivers ablative doses of radiation that cause necrosis of the irradiated tissue
- Uses specially equipped linear accelerators and modern immobilization devices
- Employs sophisticated imaging methods for precise targeting
- Typically administers treatment in 1-5 fractions (sessions)
- Does not require hospitalization or complicated preparation 2
Technical Components
SBRT requires:
- Advanced image guidance systems
- Precise patient immobilization devices
- Respiratory motion management techniques
- Highly conformal treatment planning systems
- Quality assurance protocols to ensure accurate dose delivery 1
Common Dose Fractionation Schemes
For spinal metastases, the most common dose-fractionation schemes include:
- 16-24 Gy in 1 fraction
- 24 Gy in 2 fractions
- 24-27 Gy in 3 fractions
- 30-35 Gy in 5 fractions 1
Clinical Applications
SBRT is primarily indicated for:
Early-stage primary cancers:
Oligometastatic disease (typically ≤5 lesions in ≤3 organs):
Reirradiation:
- Previously irradiated spinal metastases
- Recurrent tumors in previously treated areas 1
Clinical Outcomes
- Local tumor control: Approximately 90% at 1 year for spinal metastases 1
- Pain response: Complete pain response in approximately 50% of patients with spinal metastases 1
- Local control for lung tumors: >90% for early-stage lung cancer 3
Safety Profile
Common adverse events include:
- Vertebral compression fractures (9.4% in spinal SBRT) 1
- Radiation-induced myelopathy (rare, 1.2% in reirradiation setting) 1
- Fatigue
- Site-specific toxicities depending on treated area
Advantages Over Conventional Radiotherapy
- Higher biologically effective dose delivery
- Improved local control rates
- Shorter overall treatment time (days vs. weeks)
- Less damage to surrounding healthy tissues
- Potential for treating patients not eligible for surgery
- Outpatient treatment modality 2, 6
Integration with Other Therapies
SBRT can be combined with:
- Bisphosphonates for bone metastases 1, 4
- Systemic therapies (with appropriate timing)
- Surgical interventions (pre- or post-operative)
SBRT represents a significant advancement in radiation oncology, offering curative potential for early-stage primary tumors and effective local control for oligometastatic disease, potentially improving survival and quality of life for cancer patients.