Oligodendrogliomas: an update on basic and clinical research.

Oligodendrogliomas have been the focus of considerable interest over the past decade, ever since they were recognized as chemosensitive tumors. They were once believed to represent less than 5% of gliomas, but by using expanded criteria, they may well represent up to one third. In fact, morphologic criteria are vague and highly subjective and the histologic diagnosis, therefore, remains highly controversial and unsatisfactory. New oligodendrocytic lineage markers, such as OLIG1/2 gene, will probably help to define the real spectrum of oligodendroglial tumors, which may include a wide variety of tumors with very different prognoses. Recently, genetic markers, and particularly loss of 1p and 19q chromosomes, have been shown to predict both prognosis and response to treatment. There is little doubt that these emerging techniques will be very helpful in clinical practice for refining both classification and therapeutic indications of oligodendroglial tumors.