Benign versus atypical meningiomas: risk factors predicting recurrence.

ABSTRACT

OBJECTIVE: The aim of the study is to determine which clinic, radiologic, and surgical characteristics of benign and atypical meningioma are associated with tumor progression. METHODS: 335 patients who underwent gross-total resection of intracranial benign and atypical meningiomas between 2000 and 2009 were followed during the period of at least 3 years. Clinical, radiological and surgical features possibly associated with progression-free survival and influencing tumor recurrence were assessed. RESULTS: 291 lesions were benign (WHO Grade I) and 44 were atypical (WHO Grade II). In the median follow-up period of 82 months 34 meningiomas recurred. The 3-, 5- and 10-year progression-free survival (PFS) rates for benign and atypical tumors were 99.7 and 81.4%, 97.5 and 69.7%, 87.5 and 69.7%, respectively. In a Kaplan-Meier analysis subpial plane of surgical dissection (pial invasion) was associated with increased tumor progression both in benign (p=0.0084) and atypical cohort (p=0.0104), and bone involvement (p=0.0033) and peritumoral brain edema (p=0.0073) were associated with increased tumor progression only in atypical meningiomas. In a multivariate analysis pial invasion and WHO Grade II type were significantly associated with tumor recurrence. All recurrences in atypical meningioma group occurred within 4 years of the surgical resection. CONCLUSION: Pial invasion is an important predictor of tumor recurrence in benign and atypical meningiomas. In atypical meningiomas bone involvement and large peritumoral brain edema are associated with increased tumor progression.