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.

Keywords: Atypical meningioma; Benign meningioma; Pial invasion; Prognosis; Tumor recurrence.