Impact of H3K27 trimethylation loss in meningiomas: a meta-analysis

Prognostic Factors and Outcomes in World Health Organization Grade 1 and Grade 2 Intracranial Meningiomas-5-Year Institutional Experience

BACKGROUND

Meningiomas are the most frequent primary intracranial tumor. While histological grade and grade of excision are established predictors of recurrence, the predictive ability of other clinical features, such as the role of radical excision of dural attachment and postoperative radiation therapy in intermediate-risk groups, remains unknown.

METHODS

Clinical and radiological features and surgical details were analyzed in 451 World Health Organization (WHO) grade 1 intracranial meningiomas and 248 WHO grade 2 meningiomas operated on between 2010 and 2015. Outcomes were assessed in 352 WHO grade 1 and 208 WHO grade 2 meningiomas, studying the effect of extent of resection and use of radiation therapy. Kaplan-Meier analysis was used to determine differences in survival by extent of resection and use of postoperative radiation therapy in the treatment of the meningiomas.

RESULTS

The mean age of the cohort was 46.3 years, with a female predominance. On univariate analysis, sex, WHO grade, and Simpson grade were significant predictors of recurrence. On multivariate analysis, WHO grade and Simpson grade remained significant predictors of recurrence. Recurrence was significantly associated with poor performance status and mortality. Postoperative radiation significantly improved progression-free survival among patients with grade 2 meningiomas who underwent gross total resection, but not among patients with grade 1 and grade 2 meningiomas who underwent subtotal resection.

CONCLUSIONS

WHO grade and Simpson grade are independent predictors of recurrence in meningiomas. Regardless of WHO grade, gross total resection must be performed when possible, and postoperative radiation therapy may be recommended in grade 2 meningiomas.

Molecular prognostication in grade 3 meningiomas and p16/MTAP immunohistochemistry for predicting CDKN2A/B status

Background

The World Health Organization 2021 classification introduces molecular grading criteria for anaplastic meningiomas, including TERT promoter (TERTp) mutations and CDKN2A/B homozygous deletion. Additional adverse prognostic factors include H3K27me3 and BAP1 loss. The aim of this study was to explore whether these molecular alterations stratified clinical outcomes in a single-center cohort of grade 3 meningiomas. Additionally, we examined whether p16 and MTAP immunohistochemistry can predict CDKN2A/B status.

Methods

Clinical and histopathological information was obtained from the electronic medical records of grade 3 meningiomas resected at a tertiary center between 2007 and 2020. Molecular testing for TERTp mutations and CDKN2A/B copy-number status, methylation profiling, and immunohistochemistry for H3K27me3, BAP1, p16, and methylthioadenosine phosphorylase (MTAP) were performed. Predictors of survival were identified by Cox regression.

Results

Eight of 15 cases demonstrated elevated mitotic index (≥20 mitoses per 10 consecutive high-power fields), 1 tumor exhibited BAP1 loss, 4 harbored TERTp mutations, and 3 demonstrated CDKN2A/B homozygous deletion. Meningiomas with TERTp mutations and/or CDKN2A/B homozygous deletion showed significantly reduced survival compared to anaplastic meningiomas with elevated mitotic index alone. Immunohistochemical loss of p16 and MTAP demonstrated high sensitivity (67% and 100%, respectively) and specificity (100% and 100%, respectively) for predicting CDKN2A/B status.

Conclusions

Molecular alterations of grade 3 meningiomas stratify clinical outcomes more so than histologic features alone. Immunohistochemical loss of p16 and MTAP show promise in predicting CDKN2A/B status.