Single-Fraction Stereotactic Radiosurgery as Primary Management of Sporadic Meningiomas: A 25-Year Cohort Study

BACKGROUND AND OBJECTIVES: Stereotactic radiosurgery (SRS) is increasingly used as a primary treatment modality for intracranial meningiomas. We aim to describe clinical outcomes after single-fraction SRS for sporadic intracranial meningiomas. METHODS: A prospectively maintained database was reviewed for patients with sporadic meningiomas who underwent SRS (Gamma Knife) as primary treatment modality from April 1997 to February 2022. Primary outcomes included progression-free survival (PFS) and treatment-related complications. RESULTS: Six hundred sixteen patients (653 tumors) underwent SRS with median follow-up of 6.3 years (interquartile range [IQR] 3.1-10.5 years). The median tumor volume was 4.5 cm 3 (IQR 2.0-8.0 cm 3 ). The median margin dose was 15.0 Gy (IQR 14.0-16.0). In-field progression was noted in 7 tumors (1.1%) and marginal progression in 2 tumors (0.3%) for a raw failure rate of 1.4%. PFS estimates at 5, 10, and 15 years were 99.8%, 99.0%, and 93.2%, respectively. Factors associated with reduced PFS on univariable analysis included older age (hazards ratio [HR] 1.14, 95% CI, 1.05-1.22, P < .001), male sex (HR 5.44, 95% CI, 1.45-20.4, P = .010), increasing tumor volume (HR 1.06, 95% CI, 0.99-1.13, P = .028), and lower tumor margin dose (HR 0.65, 95% CI, 0.43-0.97, P = .006). Treatment-related complications were noted in 56 patients (9.1%), of which 45 (7.3%) were temporary, 5 (0.8%) were minor, and 6 (1.0%) were permanent and/or required intervention. Radiosurgical parameters associated with treatment-related complications included increased number of isocenters (odds ratio [OR] 1.09, 95% CI, 1.04-1.14, P < .001), higher 12-Gy volume (OR 1.06, 95% CI, 1.03-1.09, P < .001), larger tumor volume (OR 1.06, 95% CI, 1.02-1.10, P < .001), and lower maximal dose (OR 0.90, 95% CI, 0.82-0.98, P = .11). CONCLUSION: SRS is effective as a primary treatment modality for sporadic, small-volume to medium-volume intracranial meningiomas. Pre-emptive SRS should be discussed as a safe management strategy compared with observation alone for incidentally discovered meningiomas.