WHO grade II and III meningiomas: a study of prognostic factors.

Meningiomas represent one of the largest subgroups of intracranial tumors. They are generally benign, but may show a histological progression to malignancy. Grades II and III meningiomas have been less well studied and are not well controlled because of their aggressive behaviour and recurrences. There is no consensus on therapeutic strategies and no prognostic factors are known. In order to determine these parameters, a multi-institutional retrospective analysis was performed in France with the support of the Neuro-Oncology Club of the French Neurosurgical Society. This study was performed on 199 adults treated for WHO grade II (166 patients) or grade III (33 patients) meningiomas between 1990 and 2004 in the Neurosurgery Departments of five French University Hospitals. Data on epidemiology, clinical behaviour and therapy were collected. Overall survival and progression-free survival were analysed as a function of each possible prognostic factor. For patients with grade II meningiomas, the 5- and 10-year OS rates were 78.4 and 53.3%, respectively, while, for patients with grade III meningiomas, the corresponding values were 44.0 and 14.2%. For patients with grade II meningiomas, the 5- and 10-year PFS rates were 48.4 and 22.6%, respectively, the corresponding values for patients with grade III meningiomas being 8.4 and 0%. For the grade II meningiomas, univariate analysis showed that age < 60 years (P < 0.0001) and Simpson 1 resection (P = 0.055) were associated with a longer OS. For the grade III meningiomas, univariate analysis showed that age < 60 years (P < 0.0001) and RT (P = 0.036) were associated with a longer OS. Histological grade II was found to be associated with a longer PFS (P = 0.0032) and RT reduced the PFS in grade II meningiomas (P = 0.0006) There were no other prognostic factors in terms of PFS for grades II and III meningiomas in univariate analysis. Multivariate analysis confirmed that age (< 60 years), Simpson 1 and histological grade II were independent prognostic factors for survival. This retrospective study might improve the management of grades II and III meningiomas. Prospective trials should delineate strong therapeutic guidelines for high-grade meningiomas.