CA9 and oligoastrocytoma: In Cox multivariate analysis the expression of CA IX, patient age and histological component (pure oligodendroglioma vs. mixed oligoastrocytoma) showed independent prognostic significance (p = 0.009, Exp(B) = 7.370; p = 0.003, Exp(B) = 3.422 and p = 0.022, Exp(B) = 0.351).