Furthermore, the multivariate analysis adjusted for confounding factors; extent of resection and WHO grade showed that expression of PD-L1, NFKB2 and CA9 is a prognostic factor for worse recurrence free survival in meningioma patients , independent of WHO grade and extent of resection (ANOVA p = 0.024) (Supplemental Table 3). This evidence concerns the gene CA9 and meningioma.