Radiation Therapy in the Management of Meningiomas

Although most meningiomas are benign, they have a surprisingly wide spectrum of clinical and histological characteristics. The WHO classification attempts to better predict the spectrum of clinical characteristics with a histological grading system based on statistically significant clinical-pathological correlations (1). There are three types of meningiomas in this classification; benign (WHO grade I), atypical (WHO grade II) and anaplastic (malignant; WHO grade III). Because the majority of meningiomas, 80%, fall under grade I (1), they are the ones on which the most literature is available. For grade I lesions, complete surgical removal results in a permanent cure in a high percentage of patients. However the anatomic localization of meningiomas, such as at the skull base, can make complete surgery difficult, and gross total resection only, results in control rates that vary from 44% to 90% and carry a high risk of neurologic morbidity . When surgery is incomplete, the recurrence rate is high, and patients suffer long-term morbidity, decreased survival, and the risk of histological dedifferentiation (2-7).