Radiation Therapy for Optic Pathway and Hypothalamic Low-Grade Gliomas in Children

Abstract

The long-term survival of pediatric patients with optic pathway or hypothalamic low-grade glioma (LGG) who receive radiation therapy (RT) has not been previously assessed. A retrospective study was performed of all patients with optic-hypothalamic pediatric LGG treated with RT at a single institution. Eligible patients were aged ≤21years at the time of RT and had localized LGG diagnosed by neuroimaging or histology. The median RT dose was 54Gy, delivered in 30 fractions. Event-free survival (EFS) was defined as survival without progression or secondary high-grade glioma. Days were counted from the first day of RT. Eighty-nine patients were included in the study, with a median follow-up period of 12.5years. Of the patients, 14 had neurofibromatosis type 1 (NF-1). The 10-year EFS rate was 61.9% (95% confidence interval [CI], 31.2%-82.1%) for patients with NF-1 and 67.5% (95% CI, 54.8%-77.3%) for those without NF-1. The 10-year overall survival rate was 92.3% (95% CI, 56.6%-98.9%) for patients with NF-1 and 98.4% (95% CI, 89.1%-99.8%) for those without NF-1. Pre-RT chemotherapy (which was more commonly given to younger patients) was associated with reduced EFS, whereas younger age was associated with reduced overall survival. Possible RT-induced neoplasms developed in 8 patients, including 4 with NF-1. The 10-year cumulative incidence of clinically significant vasculopathy was 7.1% (95% CI, 2.9%-13.9%); vasculopathy did not develop in any child aged >10years at the commencement of RT. RT is an effective treatment for optic-hypothalamic LGG. Older children without NF-1 have a low risk of late toxicity. RT can be considered for selected younger patients or individuals with NF-1 as a salvage treatment after progression.