Prognostic factors in oligodendroglioma

Background: A reliable marker for tumor oligodendroglial cells is not yet available, so that the histological recognition of the tumor still encounters uncertainties. There is no general agreement also on prognostic factors in oligodendroglioma. The inconsistency concerns mainly the histopathological factors. The aim of the study was recognition of prognostic factors in oligodendroglioma. Methods: In a series of ninety-eight oligodendrogliomas, including twenty mixed oligoastrocytomas, clinical [sex, age at surgery, tumor location, symptoms at presentation], therapeutic [extent of resection, year of surgery, post-operative Karnofsky score, post-operative radiotherapy, post-operative chemotherapy], histological [cell density, nuclear pleomorphism, vascular endothelial proliferation, necrosis, microcysts, mitoses, mitotic index (MI), apoptosis, apoptotic index (AI)] and immunohistochemical parameters [MIB-1 and PCNA Labeling Indexes (LIs), staining for GFAP, positivity for p53] were correlated with survival in uni-and multivariate analysis in order to identify their prognostic significance. Results: Age at surgery, extent of surgical resection, year of surgery, post operative Karnofsky score and MIB-1 LI were associated with survival in both uni-and multivariate analysis. Location, symptoms at presentation, mitoses, MI, AI, and PCNA LI showed a significant correlation with survival in uni-but not in multivariate analysis. The twenty cases of oligoastrocytomas did not show any difference in survival from pure oligodendrogliomas. Conclusions: Some clinical and therapeutic factors together with MIB-1 LI play a prognostic role. MIB-1 LI is prognostic with a cut off of 8%. Histology gives a limited contribution to the prognosis. Oligoastrocytomas had the same outcome and prognostic factors as pure oligodendrogliomas.