Atypical meningioma. A study on recurrence and disease-specific survival

To analyse the outcome of patients with WHO grade II meningioma and identify factors that may influence recurrence and survival.

Between January 2000 and October 2016, a retrospective search identified 215 WHO grade II meningiomas operated on at our institution. A survival analysis was conducted on clinical and histological criteria.

Eighteen patients (8.4%) had a previous history of grade I meningioma. The cohort underwent a total of 302 surgical resections and 29.7% received radiotherapy. Forty-one patients (19.1%) had been re-operated on for a WHO grade II meningioma relapse. Median follow-up was 4.5 years. At the end of the study, 105 patients (53.6%) had no residual tumour on the last scan. Surgical recurrence-free survival at 5 years was 82%, 95% CI [75.9-88.5]. Secondary grade II meningioma (HR=4.27, P=0.001), Simpson resection grade 1 and 2 vs. 3, 4 and 5 (HR=0.25, P=0.001) and, Ki-67 index (HR=0.22, P<0.001) were independently associated with the surgical recurrence-free survival. Forty-four patients died from their tumours (20.5%). Cause-specific survival probability at 5 years was 83.2%, 95% CI [77.6-89.1]. Age at diagnosis (HR=0.31, P<0.001), Simpson resection grade 1 and 2 vs. 3, 4 and 5 (HR=0.32, P<0.001) and, redo surgery for recurrence (HR=2.39, P=0.010) were independently associated with the cause-specific survival. Patients who received radiotherapy did not demonstrate either a reduced risk of recurrence or a longer survival (P=0.280).

In this large series, atypical meningioma recurrence correlated with progression from grade I to II, incomplete resection and high Ki-67 index; shorter survival with an older age, incomplete resection, and redo surgery for recurrence. We did not observe a significant improvement in any of the clinical outcomes after radiotherapy.