High risk of recurrence for grade II meningioma: a 10-year multicenter analysis of prognosis factors.

Background: Atypical meningioma is a variant of meningioma with a high risk of recurrence. Gross total resection is the standard of treatment, while no consensus on optimal adjuvant management has been found.

Methods: Between 2008 and 2018, a retrospective search identified 216 grade II meningiomas treated in six centers. Clinical, histological, and therapeutic data were analyzed to determine the prognostic factors of recurrence and survival.

Results: In total, 216 patients underwent surgical resection. Among these, 122 patients (56%) underwent gross total resection, and 21% of the patients received adjuvant radiotherapy. Univariate analysis reported subtotal resection, high Ki-67, negative progesterone receptor (PR) and histological grade evolution as unfavorable prognosis factors. According to multivariate analysis, the Ki-67 proliferative index (cut-off value of 17.5%) was the only prognostic factor of recurrence (HR 1.1; 95% CI, 1.0-1.2, P=0.048). Gross total resection improved progression-free survival (PFS) (P=0.03) but without impact on overall survival (OS) (P=0.2). Median PFS and OS times were longer for patients receiving adjuvant radiotherapy than those who did not receive adjuvant radiotherapy. PFS (P=0.3) and OS (P=0.7) were associated with adjuvant RT by trend only. After a median follow-up time of 6.7 years, 99 (46%) patients relapsed. Median progression-free and OS rates were 4.5 (95% CI, 3.5-5.5) and 14.7 years (11.4-NA), respectively.

Conclusions: In this study, Ki-67 proliferative index was significantly associated with recurrence. Gross total resection significantly improved PFS without impacting OS. Adjuvant radiotherapy delayed recurrence and improved OS, but a longer follow-up time is needed to distinguish a statistically significant difference. Large prospective studies are needed to determine postoperative treatment guidelines.