208 Proposed Revision to Meningioma Classification System to Utilize Methylation Status of EGFR

Abstract

INTRODUCTION: Meningiomas are among the most common brain tumors, making up about 13-26% of all intracranial tumors. They arise from the arachnoid cap and most commonly appear along the lining of the skull base and the venous cavities. The current classification system for meningiomas was established by the World Health Organization (WHO) and designates tumors as WHO grades I-III depending on histological characteristics. While WHO grade does strongly correlate with tumor recurrence, it has serious shortcomings. In particular, some WHO grade I tumors, which are supposedly benign, end up becoming highly aggressive and recurrent. A more accurate method of classifying tumors to provide better insight into prognosis is needed. Epidermal growth factor receptor (EGFR) is a highly expressed protein in meningiomas that has been linked to angiogenesis and other tumor-promoting properties. METHODS: A retrospective chart analysis was first performed to gather clinical and demographic information for 291 patients diagnosed with meningioma and treated with surgical intervention. Primary tissue samples were available for 25 patients and an analysis of EGFR promoter methylation status was performed. RESULTS: A significant association was found between EGFR promoter methylation and tumor recurrence (p = 0.02176*). Of note, there was a 100% positivity rate for EGFR hypermethylation in patients with tumor progression within 10 months post-surgery (n =9). Every tumor sample classified as WHO grade II-III had EGFR hypermethylation (n = 10), as well as 7 out of the 15 WHO grade I tumors. In total, over half of the meningioma patients with EGFR hypermethylation had tumor progression within 10 months of surgery. CONCLUSION: These findings suggest that assessing methylation status of EGFR could be a valuable tool for identifying highly aggressive meningiomas and determining patient prognosis early in the game. This would allow for improved postoperative treatment regimens to be developed, reducing the chances of tumor progression.