Gamma Knife radiosurgery for neurofibromatosis type 2-associated meningiomas: a 22-year patient series

Skull Base Meningiomas in Patients with Neurofibromatosis Type 2: An International Multicenter Study Evaluating Stereotactic Radiosurgery

Objective  Meningiomas are the second most common tumors in neurofibromatosis type 2 (NF-2). Microsurgery is challenging in NF-2 patients presenting with skull base meningiomas due to the intrinsic risks and need for multiple interventions over time. We analyzed treatment outcomes and complications after primary Gamma Knife radiosurgery (GKRS) to delineate its role in the management of these tumors. Methods  An international multicenter retrospective study approved by the International Radiosurgery Research Foundation was performed. NF-2 patients with at least one growing and/or symptomatic skull base meningioma and 6-month follow-up after primary GKRS were included. Clinical and radiosurgical parameters were recorded for analysis. Results  In total, 22 NF-2 patients with 54 skull base meningiomas receiving GKRS as primary treatment met inclusion criteria. Median age at GKRS was 38 years (10-79 years). Most lesions were located in the posterior fossa (55.6%). Actuarial progression free survival (PFS) rates were 98.1% at 2 years and 90.0% at 5 and 10 years. The median follow-up time after initial GKRS was 5.0 years (0.6-25.5 years). Tumor volume at GKRS was a predictor of tumor control. Lesions >5.5 cc presented higher chances to progress after radiosurgery ( p  = 0.043). Three patients (13.64%) developed adverse radiation effects. No malignant transformation or death due to meningioma or radiosurgery was reported. Conclusions  GKRS is effective and safe in the management of skull base meningiomas in NF-2 patients. Tumor volume deserve greater relevance during clinical decision-making regarding the most appropriate time to treat. GKRS offers a minimally invasive approach of particular interest in this specific group of patients.

Neurofibromatosis type 2-associated meningiomas: an international multicenter study of outcomes after Gamma Knife stereotactic radiosurgery

OBJECTIVE

The management of neurofibromatosis type 2 (NF2)-associated meningiomas is challenging. The role of Gamma Knife radiosurgery (GKRS) in the treatment of these tumors remains to be fully defined. In this study, the authors aimed to examine the role of GKRS in the treatment of NF2-associated meningiomas and to evaluate the outcomes and complications after treatment.

METHODS

Seven international medical centers contributed data for this retrospective cohort. Tumor progression was defined as a ≥ 20% increase from the baseline value. The clinical features, treatment details, outcomes, and complications were studied. The median follow-up was 8.5 years (range 0.6-25.5 years) from the time of initial GKRS. Shared frailty Cox regression was used for analysis.

RESULTS

A total of 204 meningiomas in 39 patients treated with GKRS were analyzed. Cox regression analysis showed that increasing the maximum dose (p = 0.02; HR 12.2, 95% CI 1.287-116.7) and a lower number of meningiomas at presentation (p = 0.03; HR 0.9, 95% CI 0.821-0.990) were predictive of better tumor control in both univariable and multivariable settings. Age at onset, sex, margin dose, location, and presence of neurological deficit were not predictive of tumor progression. The cumulative 10-year progression-free survival was 94.8%. Radiation-induced adverse effects were noted in 4 patients (10%); these were transient and managed medically. No post-GKRS malignant transformation was noted in 287 person-years of follow-up.

CONCLUSIONS

GKRS achieved effective tumor control with a low and generally acceptable rate of complications in NF2-associated meningiomas. There did not appear to be an appreciable risk of post-GKRS-induced malignancy in patients with NF2-treated meningiomas.

Convexity Meningiomas in Patients with Neurofibromatosis Type 2: Long-Term Outcomes After Gamma Knife Radiosurgery

BACKGROUND

Convexity meningiomas are common tumors requiring treatment in patients with neurofibromatosis type 2 (NF2). Although different therapeutic options are described for sporadic convexity meningioma, much less is known about these lesions in patients with NF2 despite their distinct biology and need for multiple treatments. We analyzed the value of Gamma Knife radiosurgery (GKRS) as definitive treatment for convexity meningiomas in patients with NF2.

METHODS

This international multicenter retrospective study was approved by the International Radiosurgery Research Foundation. Patients with NF2 with at least 1 convexity meningioma and 6-month follow-up after primary GKRS were included.

RESULTS

Inclusion criteria were met by 18 patients with NF2. A total of 120 convexity meningiomas (median treatment volume, 0.66 cm3 [range, 0.10-21.20 cm3]) were analyzed. Median follow-up after initial GKRS was 15.6 years (range, 0.6-25.5 years). Median age at GKRS was 32.5 years (range, 16-53 years). Median number of meningiomas per patient was 13 (range, 1-27), and median number of convexity lesions receiving GKRS per patient was 3.5 (range, 1-27). One case of tumor progression was reported 24 years after GKRS, leading to actuarial progression-free survival rates of 100% at 2, 5, and 10 years. No malignant transformation or death due to meningioma or radiosurgery was recorded.

CONCLUSIONS

GKRS is safe and effective as definitive treatment of small to medium-sized convexity meningiomas in patients with NF2. Despite concerns about the particular mutational burden of these tumors, no malignant transformation manifested after treatment. GKRS represents a minimally invasive option that offers long-term tumor control to this specific group of patients.

Glioblastoma multiforme as a secondary malignancy following stereotactic radiosurgery of a meningioma: case report

The documentation and exact incidence of stereotactic radiosurgery (SRS)-induced neoplasia is not well understood, with most literature restricted to single case reports and single-center retrospective reviews. The authors present a rare case of radiosurgery-induced glioblastoma multiforme (GBM) following radiosurgical treatment of a meningioma. A 74-year-old patient with a sporadic meningioma underwent radiosurgery following surgical removal of a WHO grade II meningioma. Eighteen months later she presented with seizures, and MRI revealed an intraaxial tumor, which was resected and proven to be a glioblastoma. As far as the authors are aware, this case represents the third case of GBM following SRS for a meningioma. This report serves to increase the awareness of this possible complication following SRS. The possibility of this rare complication should be explained to patients when obtaining their consent for radiosurgery.

Validation of a scoring system to evaluate the risk of rapid growth of intracranial meningiomas in neurofibromatosis type 2 patients

OBJECTIVE

Intracranial meningiomas occur in about half of neurofibromatosis type 2 (NF2) patients and are very frequently multiple. Thus, estimating individual meningiomas' growth rates is of great interest to tailor therapeutic interventions. The Asan Intracranial Meningioma Scoring System (AIMSS) has recently been published to estimate the risk of tumor growth in sporadic meningiomas. The current study aimed to determine predictors of rapid meningioma growth in NF2 patients and to evaluate the AIMSS score in a specific NF2 cohort.

METHODS

The authors performed a retrospective analysis of 92 NF2 patients with 358 measured intracranial meningiomas that had been observed prospectively between 2012 and 2018. Tumor volumes were measured at diagnosis and at each follow-up visit. The growth rates were determined and evaluated with respect to the clinicoradiological parameters. Predictors of rapid tumor growth (defined as growth ≥ 2 cm3/yr) were analyzed using univariate followed by multivariate logistic regression to build a dedicated predicting model. Receiver operating characteristic (ROC) curves to predict the risk of rapid tumor growth with the AIMSS versus the authors' multivariate model were compared.

RESULTS

Sixty tumors (16.76%) showed rapid growth. After multivariate analysis, a larger tumor volume at diagnosis (p < 0.0001), presence of peritumoral edema (p = 0.022), absence of calcifications (p < 0.0001), and hyperintense or isointense signal on T2-weighted MRI (p < 0.005) were statistically significantly associated with rapid tumor growth. It is particularly notable that the genetic severity score did not seem to influence the growth rate of NF2 meningiomas. In comparison with the AIMSS, the authors' multivariate model's prediction did not show a statistically significant difference (area under the curve [AUC] 0.82 [95% CI 0.76-0.88] for the AIMSS vs AUC 0.86 [95% CI 0.81-0.91] for the authors' model, p = 0.1).

CONCLUSIONS

The AIMSS score is valid in the authors' cohort of NF2-related meningiomas. It adequately predicted risk of rapid meningioma growth and could aid in decision-making in NF2 patients.

Gamma Knife Radiosurgery for Patients with Multiple Intracranial Meningiomas

OBJECTIVE

The aim of this study was to evaluate the safety and efficacy of Gamma Knife radiosurgery (GKRS) in patients with multiple intracranial meningiomas (MIMs).

METHODS

The authors performed a retrospective analysis of 42 consecutive patients (7 men and 35 women) with MIMs who underwent GKRS. The median age of the patients at the time of GKRS was 57.5 years (range, 27-77 years). A total of 115 tumors among 42 patients were identified through imaging or postoperative histopathologic examination, of which 90 were treated with GKRS.

RESULTS

Follow-up imaging studies were available for 75 tumors in 36 patients (83.3%), with a mean follow-up period of 45.0 months (range, 6.6-90.4 months); 41 patients (97.6%) received clinical follow-up for 16.7 to 106.7 months (average, 57.1 months). Local tumor control was achieved in 68 tumors (90.7%) at the last follow-up. On univariate analysis, surgical resection before GKRS more than once (P = 0.048) and high World Health Organization (WHO) classification (grades II and III) (P = 0.001) were associated with tumor progression. Patients with worsening clinical manifestation showed correlation with peritumor edema (P < 0.001) and had >2 lesions treated by GKRS (P < 0.001) on univariate analysis.

CONCLUSIONS

GKRS is a safe and effective treatment for MIMs. Variables including surgical resection before GKRS more than once, high grade WHO classification, peritumor edema, and >2 tumors treated by GKRS are predictors of unfavorable outcome after GKRS.

Efficacy and Safety of Gamma Knife Radiosurgery for Meningiomas in Patients with Neurofibromatosis Type 2: A Long-Term Follow-Up Single-Center Study

OBJECTIVE

To explore the efficacy and safety of Gamma Knife radiosurgery (GKRS) for meningiomas in patients with neurofibromatosis type 2 (NF2).

METHODS

A series of 35 consecutive patients with 99 meningiomas in our department were retrospectively included from January 2000 to December 2015. Clinical records, magnetic resonance images, and follow-up data were reviewed.

RESULTS

A total of 35 patients (25 women and 10 men) with 99 NF2-associated meningiomas were identified. All patients initially received GKRS. The patients' median age at the time of GKRS was 40 years (range, 16-61 years). The median prescription dose at the tumor margin was 13 Gy (range, 12-15 Gy). The median follow-up time was 96 months (range, 25-224 months). Twenty-nine patients received GKRS only once, and 6 patients received it multiple times. Six patients (17.1%) had radiation-related complications 7.5 ± 2.4 months after GKRS. Local control rates at 1, 3, and 5 years were 100%, 97.1%, and 90.6%, respectively. Distant control rates at 1, 3, and 5 years were 88.5%, 55.9%, and 45.5%, respectively. Five patients died of concomitant neurologic symptoms. No malignant transformation was observed during the follow-up periods in all 35 patients.

CONCLUSIONS

GKRS represents an effective and safe management strategy with minimal invasion for patients with NF2-associated meningiomas. Our data showed a high local control rate of NF2-associated meningiomas by GKRS; however, the distant control rate is low, especially in young patients. For these patients, retreatment with GKRS may still be the advisable method.

Multiple Intracranial Meningiomas: A Case Series and Review of the Literature

OBJECTIVE

To review the published data to create a more comprehensive natural history of multiple meningiomas (MM).

METHODS

A review of MM published until now was carried out through a Medline search up to August 2018. The use of the "multiple meningiomas" keyword returned 278 articles, and the characteristics analyzed in our present cohort were searched on those publications. Articles without detailed description of clinical findings, neuroimaging confirmation of tumor multiplicity, follow-up at least of 5 years, and clear description of clinical findings were excluded. We added series to this review.

RESULTS

293 patients with MM were analyzed: 220 women and 73 men, with a total of 932 tumors (3.1 tumors per patient). The majority of tumors were located in the convexity (653% to 74.5%). The total number of tumors treated was 429 (43.9%): 338 (78.8%) by surgical resection and 91 (21.2%) by radiotherapy. Histopathologic description was available in 303 of 429 cases, being grade I in 272 (90.3%) cases, with a predominance of the meningothelial subtype (30.7%). Tumor recurrence was described in 32 (8.07%) among 397 and only 10 deaths (3.4%) of 281 reported cases, where this characteristic was evaluated.

CONCLUSIONS

World Health Organization grade I predominance was observed among multiple meningiomas in similarity to single meningiomas. Only a fraction of MM patients (43.89%) needed treatment. A benign tumor behavior was corroborated by the observed low frequency of recurrence and mortality.