Chemotherapy of anaplastic oligodendroglial tumours.

Anaplastic oligodendroglial tumours (oligodendrogliomas and oligoastro-cytomas) have a definite better prognosis than diffuse astrocytic gliomas (glioblastomas and anaplastic astrocytomas). Surgery relieves neurological symptoms and provides tissue for classification, grading and molecular characterisation of the tumour. Historically, radiation therapy has been the sole postoperative treatment for patients with anaplastic oligodendroglial tumours, but this policy has been challenged in the last few years by the discovery that these tumours are chemosensitive. Procarbazine, lomustine and vincristine (PCV) and temozolomide are the most active drugs, but it is still unclear which is the best first-line regimen. The most appropriate timing for chemotherapy (neoadjuvant, adjuvant, at recurrence) is unknown and is currently being explored in prospective studies. The goals of neoadjuvant chemotherapy (PCV, temozolomide, high-dose alkylating agents with stem cell rescue) are to defer radiotherapy or to reduce the radiation fields for a conformal treatment in responding patients. Molecular genetic analysis is increasingly employed for both diagnostic and prognostic purposes. Loss of heterozygosity on 1p and 19q is the key alteration for predicting the prognosis and the response to chemotherapy.