SBRT (stereotactic body radiation therapy) is a form of external beam radiation therapy that uses high doses of radiation delivered with extreme precision in a small number of treatment sessions. It provides advantages over conventional radiation therapy such as higher success rates, lower risks of side effects, and less disruption to chemotherapy. While SBRT is very effective for local control, toxicities depend on proximity to critical structures and compromises made in the treatment plan. With careful patient selection and treatment planning, SBRT can be safely used to treat primary and metastatic tumors throughout the body.

1. S B R T
I N D I C A T I O N S , B E N E F I T S A N D T O X I C I T I E S
Dr Bala Vellayappan
MBBS, FRANZCR, MCI
Consultant Radiation Oncologist
NCIS

2. S B R T
H I S T O R I C A L P E R S P E C T I V E
1951 : Lars Leksell - Gamma knife
1990s: Lax and Blomgren - Extra-cranial SBRT
@ Karolinska Institute
2000 : Uematsu - CT-guided lung SBRT
2010 : Bob Timmerman - RTOG 0236 published

3. S B R T
S T E R E O T A C T I C B O D Y R A D I A T I O N T H E R A P Y
Crossfire

4. S B R T
F R A C T I O N S I Z E
2 Gy 18 Gy

5. A D V A N T A G E S O V E R C O N V E N T I O N A L R T
Delivered over fewer fractions
Less disruption to chemotherapy
Higher success rates
Lower risks/SE

6. S B R T
3 B E N E F I T S F O R M E D O N C S T O R E M E M B E R A B O U T
1. Exceptional local control
2. Extremely convenient
3. Non-invasive ablation

7. S B R T
3 I N D I C A T I O N S O F
Early stage, medically inoperable : scapel-less surgery
Re-treatment
Oligomets : “local cure”

8. S B R T
W H A T W E C A N T R E A T W I T H
2. Metastases
Brain
Liver
Adrenal
Bone/Spine
1. Primary
Lung
Liver
Kidney
Prostate
3. Local recurrence

9. S B R T
R E S U L T S
In general, local control rates are 80 - 90 %
Depends on plan quality, dose delivered and
compromises taken
Lee P, IJROBP 2019 Apr
Ohri IJROBP 2018 p1

10. A L L P R E S C R I P T I O N S A R E N O T
E Q U A L

11. S B R T
A D O U B L E E D G E D S W O R D

12. S B R T
T O X I C I T I E S O F
Generally well-tolerated
Acute toxicity generally less than
conventional RT/chemoRT
Serious late toxicity is rare

13. T O X I C I T Y
D E P E N D S O N
P R O X I M I T Y
• Adjacent to hollow viscus
(trachea, GI tract)
• Abutting neural structures
(spinal cord, brachial
plexus etc)
• Volume effect

14. Chang JTO 2015 p577
Chang JTO 2015 p577
S B R T
F L Y W I T H C A U T I O N Z O N E F O R

16. SITE FEARED TOXICITY MITIGATING FACTORS
ESTIMATED
RATES
B R A I N R A D I O N E C R O S I S
S I Z E O F L E S I O N
F R A C T I O N A TI O N
5 - 1 0 %
B R A I N O P T I C N E R V E I N J U R Y
M A R G I N B E T W E E N 2 S T R U C T U R E S
F R A C T I O N A TI O N
< 1 %
L U N G T R A C H E A L I N J U R Y
> 2 C M S A F E T Y M A R G I N
F R A C T I O N A TI O N
< 5 %
L U N G P N E U M O N I T I S
D O S E - V O L U M E E F F E C T
N O I L D
< 5 %
L I V E R R I L D S P A R E E N O U G H N O R M A L L I V E R ( 7 0 0 C C ) < 5 %
L I V E R B O W E L I N J U R Y > 1 C M S A F E T Y M A R G I N < 5 %
S P I N E
V E R T E B R A L
C O M P R E S S I O N #
P R O P H Y L A T I C F I X A T I O N I F U N S T A B L E
F R A C T I O N A TI O N
1 0 %
S P I N E M Y E L O P A T H Y S A F E T Y M A R G I N O F 2 - 3 M M < 1 %

17. S B R T
S T E R E O T A C T I C B O D Y R A D I A T I O N T H E R A P Y - C O N C L U S I O N
High precision, Conformal
Short down time (i.e. more chemo)
Excellent local control
Safe in the right hands
One kick at the can - get it right

18. T H A N K Y O U
bala_vellayappan@nuhs.edu.sg