Prognostic role of extent of resection and adjuvant radiotherapy in de novo anaplastic meningiomas.

Purpose: Grade 3 meningiomas, although rare, are associated with high morbidity and mortality. The respective impacts of extent of surgical resection and adjuvant radiotherapy are still debated. Moreover, anaplastic meningiomas are studied in heterogenous cohort of de novo and progressive anaplastic tumors.

Methods: We conducted a retrospective multicentric study on patients operated from a de novo anaplastic meningioma between 1999 and 2021. A centralized pathological review using 2016 WHO criteria was performed for all cases. Patients with history of radiotherapy or NF2-related Schwannomatosis were excluded.

Results: Sixty-five patients were included in the study. Median progression free survival was 23 months and median overall survival was 2 years. Neither quality of resection nor adjuvant radiotherapy alone were predictive of better overall survival. Progression free survival were impacted by combination of gross-total resection and adjuvant radiotherapy (HR = 0.47 CI95% = [0.24-0.92], p = 0.027) and age at diagnosis (HR = 2.92 CI95% = [1.38-6.21], p = 0.005) in univariate analyses. Within anaplastic tumors, those graded on mitosis number had a poorer prognosis than those graded on overt anaplasia. Among anaplastic tumors with high mitotic score (> 20/10HPF), progression free survival were impacted by postoperative radiotherapy (HR = 0.44 CI95% = [0.22-0.88], p = 0.020) and gross total resection and adjuvant radiotherapy association (HR = 0.44 CI95% = [0.21-0.90], p = 0.024) in univariate analyses.

Conclusion: Simpson grade didn't show any impact on overall survival. Gross total resection + adjuvant radiotherapy favorably impacted progression free survival in our cohort of de novo anaplastic meningiomas.