Preliminary Results from a Phase II Trial of Conformal Radiation Therapy for Localized Pediatric Brain Tumors
Presenter: TE Merchant, MD
Affiliation: St. Jude Children's Research Hospital, Memphis, TN
Use of Conformal Radiation Therapy (CRT) for treatment of pediatric brain tumors has the potential for reducing toxicity and improving the therapeutic ratio.Ê The results of such treatment, and the relationships between dose, volume and CNS effects is largely unknown in this setting.Ê This report is of the St. Judes experience in treating children using this modality, with attention to local control and patterns of failure.Materials and Methods:
- 30 children with low grade astrocytoma (LGA) and 45 with ependymoma (12 malignant and 33 differentiated) were treated using CRT.
- Margins were anatomically defined (CTV) extending 1.0 cm beyond the operative margin or residual tumor and a 0.5 cm margin (planning target volume) extending beyond the CTV.
- LGA patients received a dose of 54 Gy in 1.8 Gy fractions, while ependymoma patients were treated to a dose of 59.4 Gy in 1.8 Gy fractions.
- Median followup was 18.1 months for the LGA patients and 10.0 months for the ependymoma patients
- 2 patients with LGA failed, 1 in the high dose region and one outside the high dose region
- 2 patients with ependymoma failed.Ê Both had anaplastic lesions and both failed in the high dose volume
- The failure rates were similar to those reported in other series of patients with LGA and ependymoma
- Rates and patterns of failure for children with ependymoma and LGA treated with CRT volumes described above are similar to other reported series.
- This is an intriguing report of CRT for pediatric brain tumors that suggests it is equal in efficacy to conventional RT.
- Longer followup will be needed to assess late effects and true patterns of failure since patients with these tumors can relapse over relatively long periods