Malignant Gliomas

Abstract

Malignant gliomas include some of the most aggressive and lethal brain tumor entities in adults, and the treatment of recurrent tumors and gliomas in eloquent anatomical locations remains challenging. Stereotactic radiosurgery presents a safe and effective noninvasive salvage therapy for these cases. Tightly focused external photon beams used in radiosurgery allow for high accuracy in delivering high doses to small target volumes, thus reducing therapy-related side effects to surrounding brain tissue. While investigations of SRS for newly diagnosed malignant gliomas have shown it to be a feasible and safe treatment, benefits in progression-free and overall survival are more pronounced in recurrent gliomas treated with radiosurgery. Factors that potentially influence survival after SRS treatment in malignant gliomas include patient age, performance status, total dose, dose per fraction, and number of fractions. In other rare entities such as brain stem or optic pathway gliomas, SRS presents a feasible and safe treatment alternative with potential survival benefits. Combined approaches, such as using radiosurgery in conjunction with “dose-dense” temozolomide chemotherapy or simultaneous application of angiogenesis-inhibitors, yield a potential radiosensitization effect and increased cytotoxicity for tumor cells. While treatment-associated toxicity such as radiation necrosis presents a possible complication after CyberKnife treatment, the incidence reported is very small, and careful planning and management can minimize the risk of radiation toxicity.

In conclusion, despite occasional incidence of treatment-induced toxicity, SRS represents a safe and feasible option to treat patients with recurrent malignant glioma or gliomas in proximity to critical structures with low complication rates and potential survival benefits.