World Health Organization Grade II Meningioma: A 10-Year Retrospective Study for Recurrence and Prognostic Factor Assessment

BACKGROUND: We analyzed the characteristics of patients with World Health Organization (WHO) Grade II meningioma to identify factors that may influence recurrence. MATERIALS AND METHODS: Between January 2000 and August 2015, 178 cases of WHO Grade II meningioma were operated at our institution. This population underwent a total of 224 surgical resections, and 36 patients received radiotherapy. Median follow-up was 3.6 years, and interquartile range was 1.5-6.2. RESULTS: A total of 28 patients (16.1%) were re operated for a relapse of their Grade II meningioma. The median time between the first and the second surgery was 4.2 years [interquartile range 1.4-5.3]. Surgical recurrence-free survival at 1, 2, 5, and 10 years were: 96.9% (95% confidence interval [95% CI] 94.2-99.6; 91.7%, 95% CI 87.3-96.3; 85%, 95% CI 78.6-92; and 70.8%, 95% CI 60.1-83.5), respectively. At the end of the study, 93 patients (57.8%) had no residual tumor on the last scan. Age at diagnosis (hazard ratio [HR] 0.17, 95% CI 0.05-0.56, P < 0.001), extent of resection (HR 0.22, 95% CI 0.08-0.64, P = 0.01), and Ki-67 index (HR 0.18, 95% CI 0.06-0.56, P < 0.001) were independent factors associated with the surgical recurrence-free survival. CONCLUSIONS: Younger patients with a lower proliferation rate and gross total resection are less likely to undergo a reintervention for WHO Grade II meningioma recurrence. Observation rather than systematic adjuvant radiotherapy may be preferred. If possible, a redo surgery may be considered in case of relapse or tumor residual progression, because radiotherapy may not decrease the surgical recurrence-free survival after complete or incomplete resection.