OS8.3 Gamma knife radiosurgery for large meningiomas: 10 years of experience

Abstract BACKGROUND The use of gamma knife radiosurgery for the treatment of intracranial meningiomas has been established as an effective and safe treatment modality. Larger meningiomas are typically managed by surgery followed by radiosurgery. For situations where patients are not amenable to surgery fractionated stereotactic radiotherapy is the traditionally suggested treatment. Treatment of large meningiomas (usually defined as >10 cc) by stereotactic radiosurgery has been investigated in some recent reports, either by single-session, volume-staged or hypofractionation technique. However, there are no long-term results. The purpose of this study is to assess the long-term efficacy and safety of gamma knife radiosurgery for large (15 cc or more) intracranial meningiomas. MATERIAL AND METHODS In this study we included 80 patients with large meningiomas (³ 15 cc) who were followed up for more than 5 years. Non-benign meningiomas were excluded. Also, meningiomatosis and NF2 patients were not included. There were 18 males (22.5%) and 62 females (77.5%). The mean age was 46 years (20–83 years). Twenty-six patients (32.5%) had previous surgery. Tumor were supratentorial in 14 (17.5%) patients and skull base in 66 (82.5%) patients. The mean tumor volume was 22.3 cc (15–57.3 cc). The mean prescription dose was 11 Gy (9–12 Gy). RESULTS The mean follow up period was 8.4 years (5–17 years). The tumor shrank in 43 patients (54%), was stable in 30 patients (37%) and progressed in 7 patients (8%). The tumor control rate was 91%. Adverse radiation effects were observed in 11 patients (14%) but only 5 (6.5%) were symptomatic. These were temporary in all cases. CONCLUSION Gamma knife radiosurgery provides an effective and safe treatment option for large meningiomas. Low margin dose appears to be sufficient for tumor control. Surgery remains the first option in these cases.