Background
Retrospective matched-cohort analysis (Mayo Clinic). N=198 WHO grade I (benign) intracranial meningiomas: 62 treated with Gamma Knife stereotactic radiosurgery (SRS), 136 with microsurgery. Inclusion: tumor diameter ≤35 mm; cavernous sinus, skull base, convexity, parasagittal locations. Groups matched by age, sex, tumor location.
Interventions and follow up
Arm A (SRS): Gamma Knife stereotactic radiosurgery (n=62) for WHO grade I meningioma ≤35 mm
Arm B (Microsurgery): Resection (n=136), matched on age, sex, tumor location
Primary endpoint: 5-year tumor control and complication-free survival
mFollow up: SRS median 64 months; surgery median 81 months
Arm B (Microsurgery): Resection (n=136), matched on age, sex, tumor location
Primary endpoint: 5-year tumor control and complication-free survival
mFollow up: SRS median 64 months; surgery median 81 months
Results
SRS 5-yr tumor control: 93%
Surgery 5-yr tumor control: 86% (GTR subset 96%)
SRS complication-free survival: 92%
Surgery complication-free survival: 88%
Surgery 5-yr tumor control: 86% (GTR subset 96%)
SRS complication-free survival: 92%
Surgery complication-free survival: 88%
Adverse events
SRS: symptomatic peritumoral edema 4.8%, cranial neuropathy 4.8%, radiation necrosis <2%
Surgery: cranial nerve deficit 12.5%, wound complications 5.1%, CSF leak 3.7%, reoperation 10.3%
Mortality: SRS 0%, surgery 0.7%
Surgery: cranial nerve deficit 12.5%, wound complications 5.1%, CSF leak 3.7%, reoperation 10.3%
Mortality: SRS 0%, surgery 0.7%
Conclusions
SRS and microsurgery achieved equivalent 5-year tumor control for small to medium benign meningiomas, with comparable complication-free survival. SRS was particularly advantageous for skull base and cavernous sinus locations where complete surgical resection is often not feasible.
Key Limitations
Retrospective matched-cohort, not randomized — residual selection bias despite matching (SRS tumors smaller/more surgically inaccessible). Single-institution. Shorter SRS follow-up than surgery (64 vs 81 months) may underestimate late SRS recurrence. WHO grade I only; pre-molecular era.
Clinical Context
Influential comparative-effectiveness data supporting SRS as a definitive alternative to surgery for small-to-medium benign meningiomas, especially skull base/cavernous sinus tumors where resection morbidity is high. Reinforces SRS as a standard option in current radiation oncology and neurosurgery practice.