Linear accelerator-based radiosurgery in the management of skull base meningiomas

From May 1994 to December 1999, 43 patients with meningiomas in the base of the skull underwent linear accelerator (LINAC)-based stereotactic radiosurgery (SRS) at Chung Gung Memorial Hospital. SRS was performed as a primary treatment in 14 patients, and after resection in 29 patients. The mean tumor volume was 5.68 cc, and the mean target surface dose was 16 Gy, delivered with an average of three isocenters. The median follow-up was 74.5 months. The 7-year local control rate and 7-year overall survival rate were 89.7% and 80.2%, respectively. The 7-year local control was 100% and 84.4% in SRS alone group and surgical excision with SRS group (p = 0.21), respectively. A stationary tumor following SRS was seen in 23 (53.5%) patients, partial shrinkage was seen in 16 (37.2%) patients, and complete disappearance in one patient was seen (2.3%). Furthermore, disease progression was noted in three (7%) patients, one of whom died of disease. The median time to tumor response was 15.4 months (range 5.8-52.8 months). Cases remained stable or had improved neurological statuses without any deterioration in 37.9% and 78.7% of the groups treated with surgery and SRS and SRS alone, retrospectively. In summary, LINAC-based SRS is an effective and safe modality of treating unresectable or partially resected meningiomas in the base of the skull. For tumors with diameters of 3 cm or less, particularly in patients without or with minimal clinical neurological symptom, SRS alone can provide a good local control without causing cranial neuropathy.