Treatment of Asymptomatic Meningioma With Gamma Knife Radiosurgery: Long-Term Follow-up With Volumetric Assessment and Clinical Outcome

BACKGROUND: Some patients are diagnosed with asymptomatic meningioma(s) after undergoing a screening CT and MRI for minor ailments or postresection. OBJECTIVE: To help clinicians in decision making for treatment of asymptomatic meningiomas. METHODS: A single center retrospective cohort study of 117 patients with 122 tumors treated with Gamma Knife radiosurgery (GKRS; Elekta AB, Stockholm, Sweden). Patients were followed with longitudinal imaging and clinical evaluations. Tumor volumetry and developments of new signs or symptoms after GKRS were the end points in the study. RESULTS: Median patient age at GKRS was 60 yr (range 21-86 yr) with a median clinical follow-up of 53 mo (range 20-252 mo). The median pre-GKRS tumor volume was 3.6 +/- 3.8 cc (+/- standard deviation). Tumors were treated with a median margin dose of 14 +/- 2 Gy. At last follow-up, median tumor volume was 2.5 +/- 3.6 cc. Radiological progression-free survival (PFS) rates were 97% and 94.4% at 5 yr and 10 yr, respectively. Clinical PFS rates were 86% and 70% at 5 yr and 10 yr, respectively. Development of neurological complications was seen in 21 (18%) patients, and 11 (52%) of them had undergone surgical resection prior to GKRS. CONCLUSION: GKRS is a reasonable treatment strategy for asymptomatic meningiomas and compares favorably to natural history studies in terms of tumor control and neurological preservation. It results in relatively low morbidity in previously untreated meningiomas and serves as an appealing alternative treatment modality for recurrent meningiomas in asymptomatic patients.