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Early outcomes after stereotactic radiosurgery for growing pilocytic astrocytomas in children
S C Somaza1, D Kondziolka, L D Lunsford
1Department of Neurosurgery, University of Pittsburgh Medical Center, Pa., USA.
Insights
Stereotactic radiosurgery is a safe and effective treatment for children with deep-seated pilocytic astrocytomas. This approach offers a viable alternative to traditional radiotherapy, minimizing risks and improving outcomes.
Area of Science:
- Pediatric Neurosurgery
- Radiation Oncology
- Neuro-oncology
Background:
- Pilocytic astrocytomas are common pediatric brain tumors, often requiring multimodal treatment.
- Unresectable or residual tumors pose challenges for optimal management.
- Stereotactic radiosurgery (SRS) offers precise radiation delivery for deep-seated lesions.
Purpose of the Study:
- To evaluate the efficacy and safety of SRS as an adjuvant therapy for pediatric pilocytic astrocytomas.
- To assess tumor response and long-term outcomes in children treated with SRS.
- To compare SRS with conventional fractionated radiotherapy for small-volume tumors.
Main Methods:
- Retrospective review of 9 pediatric patients with unresectable pilocytic astrocytomas treated with SRS.
- Tumor locations included the pons, midbrain, cerebellar peduncle, thalamus, temporal lobe, hypothalamus, and caudate nucleus.
- Mean SRS dose was 15 Gy (range, 12-18 Gy); mean follow-up was 19 months.
Main Results:
- Significant tumor size reduction in 5 patients; stable disease (no further growth) in 4 patients.
- No early or delayed morbidity observed following SRS.
- SRS demonstrated a favorable safety profile and therapeutic effectiveness.
Conclusions:
- Gamma Knife radiosurgery is a safe and effective option for pediatric pilocytic astrocytomas.
- Conformal SRS targeting precisely irradiates small tumor volumes, sparing surrounding brain tissue.
- SRS may reduce surgical morbidity and potential long-term sequelae associated with fractionated radiotherapy.
Abstract:
To examine the role of stereotactic radiosurgery in the adjuvant management of children with growing and unresectable deep-seated pilocytic astrocytomas, we reviewed our experience in 9 patients. The tumors were located in the dorsolateral pons (n = 2), midbrain (n = 1, cerebellar peduncle (n = 2), thalamus (n = 1), temporal lobe (n = 1), hypothalamus (n = 1), and caudate nucleus (n = 1). The mean tumor diameter was 16 mm (range, 11-25 mm). Seven patients had prior partial tumor resection, and 2 had a stereotactic biopsy. Two patients had failed fractionated radiotherapy and 7 were considered at risk for adverse radiation effects because of their age. The mean dose to the tumor margin at radiosurgery was 15 Gy (range, 12-18). During mean follow-up of 19 months (range 13-41 months), there was a marked decrease in tumor size in 5 patients; 4 patients had no further growth. No early or delayed morbidity was associated with radiosurgery. Gamma knife radiosurgery proved a safe and effective therapeutic tool in the management of children with deep, small volume pilocytic astrocytomas. Because this tumor often appears well-delineated on contrast-enhanced neuroimaging, we believe that conformal radiosurgical targeting accurately irradiates tumor cells. For small tumor volumes it can be used in place of fractionated larger-field radiotherapy. The ability to treat the tumor yet spare surrounding brain may reduce the surgical morbidity associated with attempted radical resection and the potential cognitive and endocrine disabilities associated with fractionated radiation therapy.