Stereotactic Radiosurgery for Atypical (World Health Organization II) and Anaplastic (World Health Organization III) Meningiomas: Results From a Multicenter, International Cohort Study

Abstract

BACKGROUND Atypical and anaplastic meningiomas have reduced progression-free/overall survival (PFS/OS) compared to benign meningiomas. Stereotactic radiosurgery (SRS) for atypical meningiomas (AMs) and anaplastic meningiomas (malignant meningiomas, MMs) has not been adequately described. OBJECTIVE To define clinical/radiographic outcomes for patients undergoing SRS for AM/MMs. METHODS An international, multicenter, retrospective cohort study was performed to define clinical/imaging outcomes for patients receiving SRS for AM/MMs. Tumor progression was assessed with response assessment in neuro-oncology (RANO) criteria. Factors associated with PFS/OS were assessed using Kaplan-Meier analysis and a Cox proportional hazards model. RESULTS A total of 271 patients received SRS for AMs (n = 233, 85.9%) or MMs (n = 38, 14.0%). Single-fraction SRS was most commonly employed (n = 264, 97.4%) with a mean target dose of 14.8 Gy. SRS was used as adjuvant treatment (n = 85, 31.4%), salvage therapy (n = 182, 67.2%), or primary therapy (1.5%). The 5-yr PFS/OS rate was 33.6% and 77.0%, respectively. Increasing age (hazard ratio (HR) = 1.01, P < .05) and a Ki-67 index > 15% (HR = 1.66, P < .03) negatively correlated with PFS. MMs (HR = 3.21, P < .05), increased age (HR = 1.04, P = .04), and reduced KPS (HR = 0.95, P = .04) were associated with shortened OS. Adjuvant versus salvage SRS did not impact PFS/OS. A shortened interval between surgery and SRS improved PFS for AMs (HR = 0.99, P = .02) on subgroup analysis. Radiation necrosis occurred in 34 (12.5%) patients. Five-year rates of repeat surgery/radiation were 33.8% and 60.4%, respectively. CONCLUSION AM/MMs remain challenging tumors to treat. Elevated proliferative indices are associated with tumor recurrence, while MMs have worse survival. SRS can control AM/MMs in the short term, but the 5-yr PFS rates are low, underscoring the need for improved treatment options for these patients.

Single-fraction Stereotactic Radiosurgery for Atypical Meningiomas (WHO grade II): Treatment Results Based on a 25-year Experience

“…We did not nd that higher radiation doses correlated with improved tumor control. This is nearly identical to the 5-year PFS after SRS for patients with AM in the multicenter study of Shepard et al (36%), [19] and after EBRT in Radiation Therapy Oncology Group (RTOG) 0589 study (40%).…”

“…A number of studies advocate upfront adjuvant EBRT, [8][9][10] some reports favor post-operative surveillance with salvage radiotherapy especially for those following GTR, [11][12][13]18] while a third group advocate for SRS either as an adjuvant or salvage technique. [15,17,19,20] We found that upfront adjuvant SRS and salvage SRS for late recurrences were equally effective, whereas salvage SRS for early recurrence (7-18 months following resection) was a signi cant risk for tumor progression. One explanation may be that patients with earlier disease progression have more aggressive tumors, perhaps related to increased proliferation indices, which has been correlated with reduced e cacy after SRS of AM and MM.…”

“…The retrospective, multicenter study conducted by International Radiosurgery Research Foundation included 271 patients (AM, n=233; MM, n=38) having SRS; 55 patients (20%) had prior EBRT. [19] Increasing age and a Ki-67 index > 15% negatively correlated with PFS. Prior EBRT was associated worse PFS (P = 0.01) and an increased risk of ARE (P = 0.04) in univariate analysis but was not a signi cant factor in multivariable analysis (PFS, P = 0.06; ARE, P = 0.1).…”

“…Prior studies generally support the concept that prior EBRT adversely affects outcomes after SRS of AM. [17][18][19][20] Zhang and colleagues reported 53 patients (AM, n=44; MM, n=9) undergoing CyberKnife SRS (median dose, 20 Gy; median number of fractions, n=1). [20] Twenty patients (38%) had undergone prior EBRT.…”

“…[8][9][10][11][12][13][14] Stereotactic radiosurgery (SRS) is also frequently employed for patients with residual or recurrent AM. [15][16][17][18][19][20] These studies are typically comprised of a heterogeneous group of patients including both AM and MM, patients with genetic conditions such as neuro bromatosis or meningiomatosis, and radiation-induced tumors.…”