Linear accelerator-based stereotactic radiosurgery of intracranial meningiomas: results of the first 5 years of clinical practice.

Meningiomas are mostly benign but some are atypical or malignant. Surgical resection is curative when complete removal of benign meningiomas is contemplated. Incompletely excised and recurrent tumors are frequently treated with fractionated radiation therapy or stereotactic radiosurgery. The purpose of this study is to evaluate the short-term radiological and functional outcomes of a single center using linear accelerator (Linac) stereotactic radiosurgery for the treatment of intracranial meningiomas. Twenty-nine patients (12 males and 17 females) with 30 meningiomas, in different brain locations (skull base and non-skull base meningiomas), were treated with Linac-based stereotactic radiosurgery. The mean tumor volume was 6.3 cm³, and the mean tumor marginal and maximum doses were 10.9 and 15 Gy, respectively. The median prescribed isodose line was 80%. The patients were followed-up for a minimum of 3 years. Regarding radiological outcome, nine (30%) meningiomas demonstrated evident volume reduction, 19 (63.3%) meningiomas remained unchanged, and two (6.7%) meningiomas increased in size after radiosurgery. The local tumor control rates for skull base meningiomas and non-skull base meningiomas after radiosurgery were 90.9% and 100%, respectively. Regarding functional outcomes, 64% of patients presenting with cranial neuropathies showed improvement of their cranial nerve functions and 29% of patients remained unchanged. One patient had temporary trigeminal neuropathy. Although radiosurgery for meningiomas is generally effective and quite safe in achieving high control rates with minimum morbidity over short- and intermediate-term periods of follow-up, tumor progression might occur in a delayed manner after initial apparent control for few years. We recommend continued follow-up for longer periods to better assess the long-term outcomes.