Predictors of Survival and Tumor Control After Radiosurgery for Grade 2 Meningiomas

Introduction: The management of grade 2 meningiomas can be challenging and is multimodal involving resection and irradiation. Stereotactic radiosurgery is a common option for patients with small-to-moderate residual/recurrent disease, but published data of long-term control is limited.

Methods: We reviewed consecutive patients with pathology-proven grade 2 meningiomas who underwent radiosurgery at NYU Langone Medical Center between 2011 and 2023.

Results: 97 patients (mean age 60 ± 16 years, 50:47 female:male) underwent radiosurgery for recurrent/residual disease. Twenty patients had received prior radiation. The median number of procedures was 1, with a maximum of 8. The mean follow-up was 49 (range 3-142) months. The mOS was 131 months (95%CI 91.3–NA) from first radiosurgery. The estimated survival at 5 and 10 years were 84% and 58% respectively. The mPFS was 39.6 months (95%CI 31.4-61.9). The Ki-67 and previous radiation predicted worse OS and PFS (HR 1.15, p = 0.03, HR 1.08, p = 0.004; HR 4.226, p = 0.010, HR 2.47, p = 0.004). Primarily convexity tumors were at higher risk of intracranial recurrence (HR 2.45, p = 0.003) but not death. Local tumor control at 5 years was 53% with median locomarginal progression free survival of 64.9 months (95%CI 51.8–NA). Margin dose (≥15Gy, HR 0.367, p< 0.001), minimal dose (≥12Gy, HR 0.399, p< 0.001), Ki-67 (>10%, HR 2.827, p< 0.001) were significant predictors of tumor control. In tumors with Ki-67>10%, a margin dose ≥15Gy was associated with better tumor control, but not for tumors with a Ki-67≤10%. Nine (9%) patients experienced adverse events, two of which were CTCAE grade 3 and seven grade 2 events, consisting of worsening neurologic deficit from edema.

Conclusion : Our study proves that radiosurgery is an effective option in managing residual and recurrent grade 2 meningioma. Histology, imaging characteristics, and marginal dose are important predictors of tumor control.