Long-term Tumor Control Following Gamma Knife Radiosurgery for Parasagittal Meningiomas: A Single Institution Retrospective Analysis

Introduction: Gamma Knife Radiosurgery (GKS) is commonly performed for certain parasagittal meningiomas due to subtotal resection or increased surgical risks. However, data on long-term tumor control is limited. We aimed to identify predictors of long-term tumor control after GKS, with a focus on understanding whether outcomes differ between primary and recurrent parasagittal meningiomas.

Methods: We conducted a retrospective analysis of patients with parasagittal meningiomas treated with GKS between 2015 and 2023 at an academic institution. Recurrent tumors were defined as those that had regrowth following initial treatment at presentation. Predictors of tumor control were analyzed via univariate and multivariate regression analyses.

Results: 32 patients were included (mean age: 61.4 years). Primary tumors comprised 45.2% of cases. The median tumor diameter at presentation was 17.0 mm. The median follow-up period was 31.0 months, and the mortality rate at last follow-up was 16.7%. The median total GK dose was 1500.0 cGy (Range: 1500 to 3000). At last follow-up, 74.2% of tumors exhibited local tumor control. The median progression-free survival was 70.0 months (95% CI: 36.4 to 103.6). In univariate regression analyses, recurrent tumors were associated with a significantly shorter progression time (B: -43.8 months; 95% CI: -75.1 to -12.6; p = 0.014), compared to primary tumors, while age, gender, and tumor diameter were not significant. Univariate Cox regression showed that recurrent tumors had a higher risk of progression compared to primary tumors (HR: 5.8; 95% CI: 1.1 to 29.9; p = 0.024); however, when accounting for tumor diameter in a multivariate cox regression, this relationship was no longer significant (HR: 5.2; 95% CI: 0.9 to 28.5; p = 0.058).

Conclusion : GKS is effective for achieving local control of parasagittal meningiomas, although our findings suggest that tumor status (primary vs. recurrent) may influence long-term outcomes, warranting further investigation to better understand and optimize treatment strategies.