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Permanent I-125 brain stem implants in children
P J Chuba1, L Zamarano, M Hamre
1Department of Radiation Oncology, Barbara Ann Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, MI 48201, USA.
Insights
Iodine-125 implants for pediatric brain stem tumors show safety but poor tumor control for high-grade gliomas. Further research is needed for improved outcomes in these challenging CNS malignancies.
Area of Science:
- Pediatric neuro-oncology
- Radiation oncology
- Neurosurgery
Background:
- Brain stem gliomas are aggressive pediatric central nervous system (CNS) tumors.
- Stereotactic interstitial brachytherapy offers a targeted radiation approach.
Purpose of the Study:
- To evaluate the safety and efficacy of iodine-125 (I-125) implants for pediatric CNS tumors, particularly brain stem gliomas.
- To assess tumor control and survival rates following I-125 brachytherapy.
Main Methods:
- Retrospective analysis of 28 pediatric patients treated with I-125 implants between 1988 and 1997.
- Ten patients received stereotactic implantation in the brain stem region for glioma.
- Combined external beam radiation with fractionated stereotactic boost followed by I-125 interstitial therapy.
Main Results:
- No surgical complications were reported with catheter placement.
- Four patients died within 7-9 months; four survived for 5-38 months (median 10 months).
- Autopsies revealed progressive glioblastoma multiforme and necrosis; one patient with midbrain low-grade glioma (LGA) showed necrosis without tumor.
Conclusions:
- Stereotactic interstitial brachytherapy with I-125 is safe for pediatric brain stem tumors.
- Tumor control remains a significant challenge for high-grade brain stem gliomas despite high focal radiation doses.
- I-125 implants may have a role in managing pediatric CNS malignancies, warranting further investigation.
Abstract:
Between 1988 and 1997, 28 children have had iodine-125 implants for CNS tumors performed in our institution. Ten had stereotactic implantation in the brain stem region, and nine had the diagnosis of brain stem glioma (8 diffuse pontine, 1 midbrain tumor). Their ages ranged from 1.8 to 12 years. All patients had histological confirmation of malignancy (7 high-grade glioma, 2 low-grade glioma, 1 PNET). Diffuse pontine glioma patients received external beam radiation (50 Gy) followed by a fractionated stereotactic boost of 3 Gyx4 fractions. After 4-6 weeks, patients were reevaluated for stereotactic interstitial I-125 therapy. The planned implant dose was 82.9 Gy to the enhancing tumor (4 cGy per h). Preliminary results indicated that no surgical complications were associated with the catheter placement. Four patients have died (7-9 months from diagnosis) and four patients remain alive (5-38 months from diagnosis, median 10 months). Two autopsies confirmed the presence of progressive glioblastoma multiforme and intralesional necrosis. In one patient who received an implant alone for midbrain LGA, necrosis without tumor was found on biopsy after 36 months. He was successfully treated with hyperbaric oxygen therapy. The implementation of permanent I-125 implants appears to have a role in the management of pediatric CNS malignancy. This study confirms the results of previous reports regarding the safety of stereotactic interstitial brachytherapy in the brain stem. Tumor control for patients with high-grade brain stem glioma remains poor even with high focal radiation doses.
