WHO grade III meningioma: De novo tumors show improved progression free survival as compared to secondary progressive tumors

Abstract

Emerging evidence suggest WHO grade III meningiomas that arise de novo as opposed to dedifferentiating from a lower grade may harbor differing prognoses. To investigate this, a single institution retrospective analysis of prospectively acquired patients between 1999 and 2018 was performed. Clinical data and radiographic parameters were reviewed to calculate progression free survival and overall survival in patients undergoing microsurgical resection. Next generation targeted sequencing of meningioma associated genes was performed on 11 tumors. Eighteen patients were identified as undergoing surgical resection of WHO grade III meningioma. Nine patients (50%) had de novo arising tumors and nine patients had secondary progressive tumors. To compare outcomes, only those patients undergoing gross total resection (Simpson grade I) were included for survival analysis. There was an improvement in median progression free survival for de novo resected tumors as compared to secondary progressive tumors (p = 0.02). Median overall survival for patients with de novo tumors was not statistically improved compared to that of secondary progressive tumors (p = 0.22). Next generation sequencing of targeted genes (NF2, BAP1, TRAF7, KLF4, SMO and AKT) revealed 5/11 tumors containing mutations in the NF2 gene, 2/11 containing BAP1 mutations, and a single tumor containing mutations in both NF2 and TRAF7. More mutations in NF2 and BAP1 were seen in the secondary progressive tumors.In conclusion, patients undergoing gross total resection for de novo arising grade III meningiomas showed improved progression free survival, though similar overall survival, as compared to those patients with secondary progressive tumors. Further studies focused on tumor associated genes and other associated risk factors are needed to improve risk-stratification.