Comparative Analysis of the Prognostic Value of Simpson Grade Versus MRI-Based Extent of Resection Paradigms Across Meningioma Histomolecular Subgroups.

BACKGROUND AND

OBJECTIVES

Extent of resection (EOR) predicts local freedom from recurrence (LFFR) for meningiomas and is a key clinical trial design parameter. Simpson grade (SG) defines EOR based on intraoperative assessment of tumor removal, but MRI-based methods represent promising alternatives. The aim of this study was to compare the prognostic performance of SG vs MRI-based EOR paradigms for predicting recurrence and survival across histomolecular subgroups.

METHODS

International multicenter, retrospective cohort study included 475 meningiomas, resected between 1983 and 2024, which were classified by World Health Organization grade and molecular subgroups (DNA methylation, gene expression, and integrated grade). Area under the curve (AUC) was calculated for LFFR and overall survival (OS) from Cox models with a histomolecular subgroup and an EOR paradigm. Delta AUC (ΔAUC) compared EOR predictive performance within each subgroup, and log-rank comparisons of LFFR and OS were performed.

RESULTS

MRI-defined gross total resection was associated with significantly longer LFFR and OS when compared with subtotal resection across most histomolecular subgroups. SG1-3 vs 4 distinguished differences in LFFR across several subgroups, but there were no consistent differences in outcomes when comparing degrees of dural treatment. Multivariable Cox including gene expression groups revealed that volumetric EOR (%) had a significantly higher AUC than SG (ΔAUC 0.07, P = .036) for 5-year OS; otherwise, there were no other differences between MRI-based or SG EOR paradigms for 5-year LFFR or OS. Additional significant differences for predicting 10-year LFFR all favored MRI-based EOR paradigms.

CONCLUSION

Although SG and MRI-based EOR paradigms provide similar prognostic performance for predicting LFFR and OS in the era of molecular classification, MRI-based definitions may be preferred for future clinical trial inclusion criteria.