This document discusses the use of radiosurgery to treat pediatric brain tumors. It notes that brain tumors make up 20% of childhood cancers and radiation therapy is an important treatment. Radiosurgery aims to deliver high radiation doses to discrete tumor targets while minimizing dose to surrounding healthy tissue. The document reviews the use of radiosurgery to treat several types of benign and malignant pediatric brain tumors, including arteriovenous malformations, vestibular schwannomas, craniopharyngiomas, ependymomas, medulloblastomas, and gliomas. It finds radiosurgery can achieve high tumor control rates with low risks of complications for recurrent or residual pediatric brain tumors.

1. Radiosurgery in Paediatric tumors

2. Introduction
• Brain tumors-20% of childhood malignancies
• Radiation therapy -important treatment modality -multi-disciplinary
management
Goals of radiosurgery –
1. high doses of radiation
2. discrete target -steep dose falloff from the target
3. minimizing radiation to surrounding tissue.

3. • Radiosurgery-
1. Gammaknife based
2. Cyberknife based
3. LINAC based

4. Unique Aspects of Radiosurgery in Children
<24 months old: lack of skull thickness- complicates -
fixation of a stereotactic localization frame to the skull
child’s thin skull is that it is deformable
anesthetic concerns
difference in normal tissue tolerance between children
and adults
Gammaknife based
radiosurgery

6. • Benign CNS diseases –
1. Arteriovenous malformation (AVM)
2. Vestibular schwannoma
3. Craniopharyngioma
4. Meningiomas
• Malignant primary CNS diseases –
a) Brain metastasis
b) Ependymoma
c) Low-grade gliomas
d) High-grade gliomas
e) Medulloblastoma
f) Primitive neuroectodermal tumors (PNET)

7. Arteriovenous malformation (AVM)
• Congenital vascular abnormalities - risk of
hemorrhage.
• Primary management -surgery, embolization as
an option.
• SRS is a well-accepted -surgical risk is
unacceptable.

8. University of California, San Francisco (UCSF) evaluated dose effects on obliteration rates of 80
pediatric patients treated with SRS for AVM –
• 3-year overall obliteration rate - 56% for dose prescription of 18-20 Gy,16% - dose < 18Gy.
• 5 years following SRS, cumulative incidence of hemorrhage - 25%
• To maximixe AVM obliteration and minimize post-treatment hemorrhage, the authors recommended a
prescription marginal dose of ≥ 18 Gy.

10. KEYPOINTS-AVM
• Surgical resection -standard management for AVM.
• SRS- high rates of obliteration
low rates of post-treatment hemorrhage & neurologic complications
• Radiosurgery should be reserved for nonsurgical cases or lesions in critical
brain regions.

11. Vestibular schwannoma
• Benign, slow growing tumors
• In association with neurofibromatosis
type 2.
• Treatment options- microsurgical
resection /stereotactic radiosurgery
• Hearing preservation is important.
• Equivalence in local control ,superior
functional outcomes and quality of life
after treatment with SRS

12. A total of 55 full-text articles were included in the analysis. All studies were retrospective,
except for 2 prospective quality of life studies
The single fraction RS series (linac or Gamma Knife) with tumour marginal doses between 12 and 14 Gy
revealed 5-year tumour control rates of 90-99%, hearing preservation rates of 41-79%, facial nerve
preservation rates of 95-100% and trigeminal preservation rates of 79-99%.

13. Craniopharyngioma
• Benign tumors that arise in rathke’s pouch.
• Management -surgical resection with adjuvant fractionated radiation therapy used for residual disease.

14. 107 patients with craniopharyngioma treated with SRS to a dose of 11.5 Gy included 38 children.
Progression-free survival (PFS) at 5 and 10 years was 60.8% and 53.8%, respectively,

15. Ependymoma
• Ependymomas -small proportion pediatric brain tumors
• The standard management - maximally safe resection followed by
postoperative fractionated radiation therapy.
• Local failures -2/3 of recurrences -typically occur within the treatment field .
• SRS -residual tumor and recurrent disease.

17. Medulloblastoma
• Radiosurgery - effective and safe treatment option
• SRS- Boost after conventional fractionation
• Boston SRS series –
21 children with medulloblastoma & PNET,
six children being treated upfront with SRS (median dose 12.5 Gy) .
Median PFS -11 months & 3 year local control was 57 %.
o University of Heidelberg –
20 patients with 29 lesions -6 patients < 14 years
All recurrent disease
SRS with a median dose of 15 Gy.
There were no local failures or symptomatic radiation necrosis
•

18. Stereotactic radiosurgery or hypofractionated stereotactic radiotherapy is an effective treatment method of
the local recurrence after CSI and can be performed safely in heavily pre-treated patients

19. Gliomas
• Low Grade-
1. slow growing ,managed surgical resection alone, especially in the pediatric
population.
2. Radiosurgery - incomplete resection or recurrent disease.
• High-grade -
1. WHO grade III and IV tumors.
2. very aggressive with poor clinical outcomes.
3. Standard therapy includes resection and adjuvant radiation & chemotherapy.
4. SRS - recurrence.

21. Gammaknife Radiosurgery

22. Cyberknife radiosurgery

23. KEYPOINTS
• Radiation-induced toxicities - cognitive decline -particular concern.
• Steep dose gradient and high conformality makes radiosurgery a better option
• Valuable treatment option for children with recurrent disease.
• Challenges in establishing guidelines for pediatric -limited sample size of
treated patients compared with the adult population
• Multidisciplinary research approach i-neurosurgeons, radiation oncologists,
pediatric oncologists, anesthesiologists is paramount in optimizing the
management of children treated with radiosurgery