Gamma-knife Stereotactic Radiosurgery for Non-benign Meningioma

Abstract

Non-benign meningioma has a tendency to recur repeatedly. The results of Gamma-knife stereotactic radiosurgery (GKS) for recurrent or residual WHO grade 2 and grade 3 meningioma are reported. Thirty patients (13 males and 17 females) with WHO grade 2 (24 cases) or WHO grade 3 (6 cases) intracranial meningioma underwent GKS. Their age varied from 30 to 86 years (mean, 64 years). Location of the tumor was convexital in 6, parasagittal in 13, tentorial in 3, and skull base in 3. Before GKS, surgical resection of the tumor was done in all patients, whereas 11 of them also underwent conventional external beam radiation therapy, LINAC-based stereotactic radiation therapy (SRT), or intensity-modulated radiation therapy. At the time of the initial GKS in total 36 intracranial tumors were treated (from 1 to 3 per patient; median, 1). Their volume varied from 0.4 cc to 35.3 cc (median, 8.6 cc). The marginal irradiation dose varied from 11 Gy to 20.15 Gy (mean, 16.7 Gy). Choice of the marginal irradiation dose depended on the tumor volume and its spatial relationship with adjacent anatomical structures, particularly, cranial nerves. Twenty-five out of 30 patients were followed after initial GKS within a median period of 29 months (from 2 to 135 months). Local tumor control after treatment was 76% at 1 year, 61% at 2 years, and 41% at 3 years. Due to local or distant intracranial tumor progression, 15 patients underwent repeat GKS (from 1 to 9 times), 7 underwent surgical re-resection of the neoplasm, and 4 underwent additional SRT. At the time of the last follow-up 23 patients were alive, while 2 died. One of the latter expired due to brain tumor progression at 91 months after initial GKS, whereas another one from lung cancer. While non-benign meningioma has a trend to recur repeatedly, aggressive tumor management with repeat GKS at the time of progression can provide long survival of patients.