Anaplastic oligodendroglioma and oligoastrocytoma.

Until approximately 15 years ago, the diagnosis of an oligodendroglioma (OD) was merely as a pathologic entity. The only clinical relevant meaning of this histologic diagnosis was the observation that the prognosis of OD was in general better than that of astrocytic tumors of similar grade. This changed with the recognition of the marked sensitivity to PCV chemotherapy of these tumors, although the best timing of chemotherapy still is unclear. Observations have led to the current tendency to consider 1p/19q loss low-grade and anaplastic oligodendroglioma a separate biologic entity, at least within clinical trials, since they have a much better outcome.