WHO grade II meningioma: a retrospective study for outcome and prognostic factor assessment.

To analyse the outcome of patients with WHO grade II meningioma and identify factors that may influence recurrence and survival. Between January 2007 and September 2015, a retrospective search identified 194 WHO grade II meningiomas at the National Hospital for Neurology and Neurosurgery, London. Survival methods were implemented. 31 patients (16 %) had a previous history of grade I meningioma. The patients underwent a total of 344 surgical resections and 43.3 % received radiotherapy. 55 patients (28.4 %) had been re-operated on for a WHO grade II meningioma relapse. Median follow-up was 4.4 years. At the end of the study, 75 patients (40.1 %) had no residual tumour on the last scan. Surgical recurrence free survival at 5 years was 71.6, 95 % CI [63.5, 80.8]. Secondary grade II meningioma (HR = 2.29, p = 0.010), and, Simpson resection grade 1, 2 and 3 vs. 4 and 5 (HR = 0.57, p = 0.050) were associated with the surgical recurrence-free survival. 32 died from meningioma (16.5 %). Overall survival probability at 5 years was 83.2, 95 % CI [76.6, 90.4]. Age at diagnosis (HR = 0.22, p < 0.001), WHO grade I meningioma progressing into grade II (HR = 3.2, p = 0.001), tumour location (HR = 0.19, p < 0.001), and mitosis count (HR = 0.36, p = 0.010) were independently associated with the overall survival. Patients who received radiotherapy demonstrated neither a reduced risk of recurrence nor a longer overall survival (p = 0.310). In our series shorter survival correlated with older age, increased mitoses, progression from grade I to II and location. We were not able to demonstrate a significant improvement in any of the clinical outcomes after radiotherapy.