Gamma knife surgery for atypical meningiomas

Abstract

Object. Complete resection is the optimal treatment for atypical meningiomas (AMs) but its feasibility depends on the tumor site. The object of this study was to assess the effect of gamma knife surgery (GKS) on AM. Methods. In 15 patients 21 AMs were treated by GKS. Four patients had residual lesions and 10 patients had recurrent tumors after one or more microsurgical interventions. Three patients were treated twice with GKS because of tumor tissue outside the treatment volume, either at the margin or at a distant location. The median clinical and neuroimaging follow-up period was 35 months (range 21–67 months). Ten tumors shrank 6 to 12 months after GKS, 10 remained stable, and one grew. Between 18 and 36 months after GKS, four patients had a distant recurrence, and two had a margin recurrence. In one of these cases, an additional local recurrence was demonstrated 1 year later, and the patient underwent standard radiotherapy. No patient suffered persistent adverse effects after radiosurgery. Conclusions. After early tumor shrinkage, high recurrence rates were demonstrated both at the treatment margin and at distant locations in cases treated for AM. There was only one recurrence within the GKS radiation field. For small- and medium-sized AMs GKS may be a safe adjunct to other treatment modalities.

Risk Factors for Regrowth of Intracranial Meningiomas after Gamma Knife Radiosurgery: Importance of the Histopathological Grade and MIB-1 Index

“…In cases of WHO grade I meningiomas Kollova et al [7] recommended to choose the marginal dose within the range from 12 Gy to 16 Gy, whereas others reported that even lower doses may be used successfully [2,8] . Several previously reported series did not fi nd an association between marginal irradiation dose and growth control of non-benign meningiomas, however, in all of those reports it did not exceed 20 Gy [9,12,14] . In the mixed series of benign, atypical, and malignant meningiomas reported by Staff ord et al [3] , the marginal irradiation dose varied from 12 Gy to 36 Gy and use of lower doses was associated with worse tumor control, while such statistical signifi cance was lost when WHO grades II and III tumors had been excluded from the analysis.…”

BNCT for recurrent intracranial meningeal tumours ? case reports

“…Recurrent malignant intracranial meningeal tumours, including atypical meningioma, recurring after surgery and XRT, have been treated with radiosurgery and with proton therapy, alone or in combination with photon therapy, with good results regarding tumour control and survival times (4,5,(10)(11)(12). Reoperation followed by permanent brachytherapy with I-125 seeds has been used for malignant meningioma with survival times in the range from 6.6 to 9.4 years since initial diagnoses.…”

A Review of Stereotactic Radiosurgery Practice in the Management of Skull Base Meningiomas

“…For small (average diameter < 3 cm) or residual skull base meningiomas, SRS leads to excellent long-term control. 3,9,11,13,[17][18][19][20][21][22][23][24][25] Additionally, meningiomas associated with no or minimal surrounding edema, no elevated intra-cranial pressure, or no neurologic deficits are suitable for radiosurgery. For large skull base meningiomas (average diameter > 3 cm) or those in critical locations, SRS has been reported to provide rates of durable tumor control and low morbidity comparable with those reported with fractionated radiotherapy (FRT) and may thus be a safe treatment modality either following STR or as primary treatment in patients with significant comorbidity.…”

“…Finally, radiosurgery can be used to treat malignant meningiomas, although some consider FRT to be a better treatment option for these higher grade meningiomas. 16,22,26,27 SRS is thus an effective primary alternative to surgical resection of small to moderate size benign basal meningiomas, and as adjuvant therapy to reduce the risk of tumor recurrence and morbidity in STRs. 1,2,9…”

“…The risk of radiosurgical failure is increased for tumors of higher World Health Organization grade and for those patients who have undergone prior surgery. 22,36 Recurrent tumor growth after failed SRS, which can occur long periods (up to 14 years) after treatment, tends to be aggressive, and therefore it has been suggested that all patients should be followed > 10 years after radiosurgery. 37 One benefit of SRS is that additional radiosurgery for the treatment of tumor recurrence can be offered without the additional risks of treatment-related morbidity.…”