Exploring the Role of Radiosurgery for Atypical Meningiomas: Addressing Suboptimal Local Control in High-Risk Patients

Abstract

Purpose

Despite recent advancements in the treatment of atypical meningioma, control rates in high-risk patients continue to be suboptimal. Stereotactic radiosurgery (SRS) offers the ability to achieve improved local control (LC) with a low toxicity profile. However, available data are limited. We aimed to conduct a comprehensive review of a consecutive cohort of patients diagnosed with high-risk atypical meningioma who underwent SRS, either as a single-fraction SRS or in the hypofractionated SRS (hf-SRS), and evaluate the LC rates (LCR) with a specific emphasis on patterns of treatment failure.

Methods and Materials

We identified consecutive patients diagnosed with high-risk World Health Organization grade 2 meningioma treated with SRS at a single institution between 2014 and 2021. High-risk meningioma was defined as a residual disease or recurrence after initial gross total resection. Follow-up data were analyzed to evaluate LCRs and patterns of treatment failure. We defined local failure as tumor recurrence wthin the prescription isodose line, marginal failure as recurrence within 5 mm but outside the prescription isodose line, and distant/regional failure as recurrence beyond 5 mm of the prescription isodose line but within 2 cm of the surgical cavity.

Results

We identified 45 pathologically confirmed atypical meningiomas in 25 patients. Thirty-three tumors underwent single-fraction SRS, and 12 tumors received hf-SRS. The median follow-up was 36 months (range, 2-86 months). The 3-year LCR was 84.6%, and overall survival was 96.0%. Four patients with a total of 7 tumors experienced treatment failure. Failures were either local (3 patients and 3 lesions) or marginal (3 patients and 4 lesions). Patients treated with hf-SRS did not exhibit local, marginal, or distant failures.

Conclusions

Our institutional data on atypical patients with meningioma treated with radiosurgery compare favorably to existing literature using fractionated radiation therapy. SRS offers a promising strategy to improve LC in this patient population, and the occurrence of marginal failure plays a role in creating clinical target volume margins.