What are the typical doses of Stereotactic Body Radiation Therapy (SBRT) for different types of cancer?

SBRT Dose Recommendations by Cancer Type

For spinal metastases, use 16-24 Gy in 1 fraction, 24 Gy in 2 fractions, 24-27 Gy in 3 fractions, or 30-35 Gy in 5 fractions, with the goal of achieving a biological equivalent dose (BED) of at least 50 Gy to optimize local control rates of approximately 90% at 1 year. 1

Spinal Metastases

Common dose-fractionation schemes include:

• Single fraction: 16-24 Gy in 1 fraction 1
• Two fractions: 24 Gy in 2 fractions 1
• Three fractions: 24-27 Gy in 3 fractions 1
• Five fractions: 30-35 Gy in 5 fractions 1

Key considerations for spinal SBRT:

• The BED range across studies was 20-81.6 Gy, with 9 of 14 studies achieving a median BED of 50 Gy or higher 1
• For renal cell carcinoma spinal metastases specifically, 24 Gy in a single fraction using simultaneous integrated boost technique is appropriate 1
• These doses achieve 90% 1-year local control rates and 85% crude local control rates, substantially exceeding conventional radiotherapy 1, 2
• The most common late toxicity is vertebral compression fracture, occurring in 9.4% of patients overall 1

Lung Cancer (Early-Stage NSCLC)

For central lung tumors, use 50 Gy in 5 fractions to optimize tumor control while minimizing toxicity to critical mediastinal structures. 3

Dose stratification by tumor location:

• Central tumors (within 2 cm of mediastinal structures): 50 Gy in 5 fractions 3
• Peripheral tumors: Higher doses per fraction may be used, though specific regimens vary 3
• Ultracentral tumors (PTV overlapping trachea/main bronchi): SBRT is not appropriate due to excessive toxicity risk 3

Important dosing principles:

• The optimal BED10 should be at least 100 Gy, with ranges of 106-146 Gy showing the best outcomes 3
• Early studies using 60-66 Gy in 3 fractions for central tumors reported serious and lethal toxicity, making lower doses per fraction essential 3
• For tumors >5 cm or moderately central location in medically inoperable patients, conventional or accelerated fractionation is preferred over SBRT 3

Dose escalation based on tumor size:

• Tumors <1.5 cm: 44 Gy in 4 fractions 4
• Tumors 1.5-3 cm: 48 Gy in 4 fractions 4
• Tumors >3 cm: 52 Gy in 4 fractions 4
• Maximum dose (Dmax) ≥125 Gy (BED10) in the planning target volume improves local control, particularly for squamous cell carcinoma and T2 tumors 5

Non-Spine Bone Metastases

For non-spine bone metastases, use 15-24 Gy in 1 fraction or 24-50 Gy in 3-5 fractions, achieving approximately 90% local control with low toxicity rates. 6

Common fractionation schemes:

• Single fraction: 15-24 Gy in 1 fraction 6
• Multiple fractions: 24-50 Gy in 3-5 fractions 6

Special considerations:

• For Ewing sarcoma and osteosarcoma bone metastases, SBRT achieved 85% estimated local control in one series, though significant toxicity occurred with concurrent chemotherapy and reirradiation 1
• Conventional palliative radiation (8 Gy in 1 fraction) achieves less than 50% 1-year local control for bulky tumors and should be avoided in patients with longer expected survival 2

Radiobiological Principles Across All Sites

SBRT delivers substantially higher biological effective doses compared to conventional fractionation, typically using 6-18 Gy per fraction in 2-8 sessions. 2, 7

Key radiobiological advantages:

• Traditionally radioresistant tumors (melanoma, renal cell carcinoma, sarcoma) show excellent outcomes with SBRT, with 2-year local control rates of 90% for RCC 2
• Bulky "mass-type" tumors with extraosseous extension that achieve <50% control with conventional external beam radiation therapy benefit from higher SBRT doses 2
• SBRT achieves direct tumor cell ablation through high BED delivery, with focused beams achieving high biological effectiveness while sparing surrounding tissues 2, 7

Critical Pitfalls to Avoid

Do not use conventional low-dose palliative radiation (8 Gy in 1 fraction) for patients expected to survive long enough to experience local progression, as suboptimal doses increase spinal adverse events including cord compression. 2

• Avoid SBRT for ultracentral lung tumors where the PTV overlaps trachea or main bronchi due to unacceptable toxicity risk 3
• For central lung tumors, do not use 60-66 Gy in 3 fractions, as this has resulted in serious and lethal toxicity 3
• Ensure BED10 of at least 100 Gy for lung SBRT to optimize outcomes 3
• Use advanced dose calculation algorithms (type B models) and planning organ at risk volume margins for critical serial organs in centrally located tumors 3