The 35-Year Evolution of Stereotactic Radiosurgery for Meningiomas

BACKGROUND AND OBJECTIVES: Since the introduction of the Leksell Gamma Knife to North America in 1987, stereotactic radiosurgery (SRS) has increasingly been used for patients with intracranial meningiomas. We evaluated the evolving application and outcomes of meningioma patients managed with both primary and adjuvant SRS during a 35-year interval. METHODS: The authors reviewed the outcomes of meningioma patients (1229 female, 69.8%; 2220 tumors) who underwent single-fraction SRS from August 1987 to March 2022 and who had a minimum of 6-month follow-up. The rates of treated tumor control and overall survival up to 20 years after SRS were measured. Risk factors analyzed included age, sex, tumor volume, margin dose, Ki-67, anatomical location, and pre-SRS surgical resection. RESULTS: Primary SRS showed superior tumor control compared with adjuvant SRS after previous resection. Overall, 191 of 2220 patients (8.6%) had local progression at last follow-up with the 5-year, 10-year, 15-year, and 20-year tumor control rates were 92.1%, 88.3%, 84.1%, and 81.1%, respectively. The median overall survival after SRS was 17.4 years, and 2.6% of patients died related to meningioma progression. Patients treated so that ≥60% of the tumor received at least 16 Gy demonstrated significantly superior tumor control. Fifty-eight patients (3.3%) experienced symptomatic adverse radiation effects after SRS. CONCLUSION: SRS provided excellent local tumor control rates that extended beyond 20 years. Primary SRS was an effective strategy for patients with unresected or known WHO grade I meningiomas. Adjuvant SRS was an important option to enhance tumor control and survival in patients with residual or progressive tumors after resection.