When the cure becomes the curse: Radiation-induced glioma of the pons in children surviving craniopharyngioma.

Abstract

Background: The standard of care for pediatric craniopharyngioma (CP) is either complete surgical resection or limited debulking surgery followed by adjuvant radiotherapy (RT). Recent data favor the latter approach.

Methods: We present a multi-center case series of three children with CP treated with subtotal surgery and adjuvant RT for CP who eventually developed radiation-induced glioma (RIG) of the pons.

Results: The median age at diagnosis of CP was 6 years. Photon RT was administered in two patients and proton RT in one, at a median dose of 54 Gy delivered in 30 fractions. Pontine glioma was first identified on imaging after a median interval of 8 years from initial RT (range 4.5 - 9.75 years), incidentally in two asymptomatic patients during routine surveillance, and associated with symptoms of brainstem involvement in one. A biopsy was performed in two patients. One showed diffuse astrocytoma with MYCN, PDGFRA, and MDM2 amplification and a novel fusion (RBD7-FLI1), while the other case had an inconclusive histopathology. Re-irradiation (re-RT) (54 Gy/30 fractions and 30 Gy/10 fractions) was applied in two patients, and one patient received bevacizumab treatment. All three patients succumbed with a median survival of 7.5 months (range 4.0-58 months).

Conclusions: Radiation-induced glioma of the pons is a rare and serious complication occurring in patients previously treated by RT for childhood CP. This secondary tumor is uniformly associated with a dramatic course regardless of the treatment modalities and resources. This highlights the need for clinical vigilance and further research to prevent it.