Radiation-Induced Gliomas

Radiation therapy has been a cornerstone of cancer management for many decades and is an integral part of the multi-modality care of patients with brain tumors. The known serious side effects of radiation therapy on the head or central nervous system are uncommon and include radiation necrosis, microangiopathy, and progressive leukencephalopathy. In addition, there have been descriptions of radiation-induced tumors including sarcomas, gliomas, lymphomas, and carcinomas of the thyroid. Patients who have received radiation therapy of the head or face may rarely develop radiation-induced tumors, a majority of which are meningiomas, followed by radiation-induced gliomas (RIGs) and sarcomas. The increased risk of RIGs is well described in both the pediatric and adult populations and after the use of both therapeutic and diagnostic radiations. The incidence of RIGs is estimated at approximately 0.5-2.7% at a latent period of approximately 15 years. The risk appears to be dependent on patient age at treatment, as well as radiation dose and treatment volume considerations. The scope of this review focuses on the etiology, clinical features, and management of RIGs as they relate to previous radiation therapy.