Gamma Knife radiosurgery for posterior fossa meningiomas: a multicenter study

Abstract

abbreviatioNs CI = confidence interval; CN = cranial nerve; CPA = cerebellopontine angle; GKRS = Gamma Knife radiosurgery; HR = hazard ratio; OR = odds ratio; SRS = stereotactic radiosurgery. obJect Posterior fossa meningiomas represent a common yet challenging clinical entity. They are often associated with neurovascular structures and adjacent to the brainstem. Resection can be undertaken for posterior fossa meningiomas, but residual or recurrent tumor is frequent. Stereotactic radiosurgery (SRS) has been used to treat meningiomas, and this study evaluates the outcome of this approach for those located in the posterior fossa.methods At 7 medical centers participating in the North American Gamma Knife Consortium, 675 patients undergoing SRS for a posterior fossa meningioma were identified, and clinical and radiological data were obtained for these cases. Females outnumbered males at a ratio of 3.8 to 1, and the median patient age was 57.6 years (range 12-89 years). Prior resection was performed in 43.3% of the patient sample. The mean tumor volume was 6.5 cm 3 , and a median margin dose of 13.6 Gy (range 8-40 Gy) was delivered to the tumor.results At a mean follow-up of 60.1 months, tumor control was achieved in 91.2% of cases. Actuarial tumor control was 95%, 92%, and 81% at 3, 5, and 10 years after radiosurgery. Factors predictive of tumor progression included age greater than 65 years (hazard ratio [HR] 2.36, 95% CI 1.30-4.29, p = 0.005), prior history of radiotherapy (HR 5.19, 95% CI 1.69-15.94, p = 0.004), and increasing tumor volume (HR 1.05, 95% CI 1.01-1.08, p = 0.005). Clinical stability or improvement was achieved in 92.3% of patients. Increasing tumor volume (odds ratio [OR] 1.06, 95% CI 1.01-1.10, p = 0.009) and clival, petrous, or cerebellopontine angle location as compared with petroclival, tentorial, and foramen magnum location (OR 1.95, 95% CI 1.05-3.65, p = 0.036) were predictive of neurological decline after radiosurgery. After radiosurgery, ventriculoperitoneal shunt placement, resection, and radiation therapy were performed in 1.6%, 3.6%, and 1.5%, respectively.coNclusioNs Stereotactic radiosurgery affords a high rate of tumor control and neurological preservation for patients with posterior fossa meningiomas. Those with a smaller tumor volume and no prior radiation therapy were more likely to have a favorable response after radiosurgery. Rarely, additional procedures may be required for hydrocephalus or tumor progression.

Efficacy and outcomes of facial nerve–sparing treatment approach to cerebellopontine angle meningiomas

“…Importantly, the authors in that study reported tumor control rates of 95%, 92%, and 81% at 3, 5, and 10 years after radiosurgery, respectively. 20,22 Similarly, we found that GKRS as the initial treatment for small, mildly symptomatic lesions as well as recurrent or progressive tumors resulted in excellent disease control, and no patient treated initially with GKRS experienced progression over the follow-up period. Low rates of progression/recurrence suggest that longterm disease control for these low-grade lesions is possible with the outlined treatment algorithm, even in the setting of STR, and supports the goal of preserving neurological function whenever possible to maximize patient quality of life.…”

“…6,20 While aggressive and complete resection of meningiomas is curative, tumors arising within the CPA present unique surgical challenges com- pared with supratentorial lesions, given their close association with critical neurological and vascular structures.…”

“…Interestingly, evidence suggests that increasing tumor volume and CPA location are associated with neurological decline after radiosurgery alone and likely reflects the narrow corridor of the CPA and its intolerance of edema, resulting in compression of critical structures. 20 As a result, in the setting of larger CPA tumors, the benefits seen with smaller tumor volumes at the time of radiosurgery highlight the importance of an initial cytoreductive surgery. We suggest that GTR be attempted with a low threshold to pursue STR with adjuvant GKRS for radiographic or symptom progression.…”

“…This is in part due to the concurrent rise of Gamma Knife radiosurgery (GKRS) as an acceptable treatment modality for newly diagnosed, recurrent, or progressive meningiomas within the posterior fossa, with large series demonstrating excellent tumor control rates and minimal adverse effects. [2][3][4]8,12,20,25 In the present study, we review the experience of a single surgeon over the past 24 years in the treatment of meningiomas of the CPA treated with GKRS, surgery, or a combination. We use a treatment approach in which GKRS is the first treatment option for tumors smaller than 2.5 cm, with the option of aggressive resection using facial nerve-sparing microsurgical techniques for tumors 2.5 cm or larger with adjuvant GKRS for recurrent disease or progressive residual.…”

Adaptive fractionated stereotactic Gamma Knife radiotherapy of meningioma using integrated stereotactic cone-beam-CT and adaptive re-planning (a-gkFSRT)

“…In case of incomplete resection, recurrent, or a priori nonresectable tumors, radiotherapy is the treatment of choice. To date, two radiotherapy regimes are established: stereotactic radiosurgery (SRS) and full-course fractionated stereotactic radiotherapy (FSRT) [1][2][3]. While SRS (mostly performed with doses of 12-15 Gy) is limited to small lesions distant to critical structures, FSRT can be applied even in larger lesions in close proximity to organs at risk, using total doses of 50.4-57.6 Gy in fractions of 1.8 Gy.…”