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Radiation therapy for pilocytic astrocytomas of childhood
David B Mansur1, Joshua B Rubin, Elizabeth A Kidd
1Department of Radiation Oncology, Washington University School of Medicine and Saint Louis Children's Hospital, Saint Louis, MO 63110, USA. mansur@radonc.wustl.edu
Insights
Radiation therapy offers excellent survival for pediatric pilocytic astrocytomas, but tumor control remains a challenge, with nearly a third experiencing progression. Further research is needed to define optimal treatment strategies.
Area of Science:
- Pediatric Oncology
- Radiation Oncology
- Neuro-oncology
Background:
- Pilocytic astrocytomas are common pediatric brain tumors.
- Radiation therapy is often the primary treatment for unresectable cases.
- Limited data exist on radiation therapy's long-term efficacy in this population.
Purpose of the Study:
- To evaluate the effectiveness of radiation therapy for unresectable pediatric pilocytic astrocytomas.
- To analyze treatment outcomes and identify factors influencing progression-free survival.
Main Methods:
- Retrospective review of 35 pediatric patients (≤18 years) with unresectable pilocytic astrocytomas.
- Patients received external beam radiation therapy (median 54 Gy) or radiosurgery (median 15.5 Gy).
- Some patients received initial chemotherapy followed by radiation upon progression.
Main Results:
- Excellent survival rates observed, with all patients alive at median 5-year follow-up.
- Progression-free survival was 68.7%, with higher progression rates in supratentorial tumors.
- Radiosurgery showed a trend towards improved progression-free survival compared to external beam therapy alone.
Conclusions:
- While survival is high, definitive radiotherapy results in disease progression for a significant portion of pediatric pilocytic astrocytoma patients.
- Improved tumor control strategies are necessary.
- Prospective trials comparing initial chemotherapy with radiation therapy are warranted to determine optimal treatment.
Purpose:
Though radiation therapy is generally considered the most effective treatment for unresectable pilocytic astrocytomas in children, there are few data to support this claim. To examine the efficacy of radiation therapy for pediatric pilocytic astrocytomas, we retrospectively reviewed the experience at our institution.
Methods And Materials:
Thirty-five patients 18 years old or younger with unresectable tumors and without evidence of neurofibromatosis have been treated since 1982. Patients were treated with local radiation fields to a median dose of 54 Gy. Six patients were treated with radiosurgery to a median dose of 15.5 Gy. Five patients were treated with initial chemotherapy and irradiated after progression.
Results:
All patients were alive after a median follow-up of 5.0 years. However, progression-free survival was 68.7%. None of 11 infratentorial tumors progressed compared with 6 of 20 supratentorial tumors. A trend toward improved progression-free survival was seen with radiosurgery (80%) compared with external beam alone (66%), but this difference did not reach statistical significance. Eight of the 9 patients progressing after therapy did so within the irradiated volume.
Conclusions:
Although the survival of these children is excellent, almost one third of patients have progressive disease after definitive radiotherapy. Improvements in tumor control are needed in this patient population, and the optimal therapy has not been fully defined. Prospective trials comparing initial chemotherapy to radiation therapy are warranted.
