Intracranial Meningiomas, WHO Grade Il : Prognostic Implications of Clinicopathologic Features

OBJECTIVE: Intracranial meningiomas are primarily benign tumors with a good prognosis. Although WHO grade II meningiomas are rare (2-10%), WHO grade II meningiomas have higher recurrence and mortality rates than benign. We evaluated the patient recurrence rate and investigated the prognostic factors of WHO grade II meningiomas. METHODS: Between 1993 and 2005, 55 patients were diagnosed with WHO grade II meningiomas in our hospital. WHO grade II meningiomas (n=55) were compared with other WHO grades meningiomas (I, n=373; and III, n=20). The patients had a median age of 48.4 years (range, 14-17 years), a male-to-female ratio of 26 : 29, and a mean follow-up time of 45 months (range, 3-175 months). RESULTS: In WHO grade II meningiomas, only the extent of resection was a significant prognostic factor. Post-operative radiotherapy had no significant influence on tumor recurrence (p=0.053). The relative risk of recurrence was significantly higher in WHO grade II meningiomas with incomplete resection (10/27, RR=37%) than in WHO grade II meningiomas with complete resection (4/28, RR=14%) regardless of post-operative radiotherapy. In the incomplete resection group, Simpson grade III or IV had a significantly high risk of recurrence regardless of post-operative RT (n=3, RR=100%) However, if the degree of resection was Simpson grade II, the recurrence rate was similar to the complete resection group even though post-operative RT was not performed. CONCLUSION: Complete resection was the most powerful independent predictive factor of the recurrence rate in WHO grade II meningiomas. Post-operative adjuvant RT was not a significant factor in this study.