Oligodendrogliomas: clinicopathological correlations

Prognostic variables in oligodendroglial tumors: a single-institution study of 95 cases

We analyzed the relationships among clinical variables, histology, 1p/19q status, and outcome in 95 patients with oligodendroglial tumors. The study enrolled adult patients who underwent first-time surgery for a supratentorial oligodendroglial tumor at Oslo University Hospital, Rikshospitalet. Tumors were: 27 oligodendrogliomas, WHO grade II; 32 oligoastrocytomas, WHO grade II; 16 anaplastic oligodendrogliomas, WHO grade III; 14 anaplastic oligoastrocytomas, WHO grade III; and 6 glioblastomas with a major oligodendroglial component, WHO grade IV. The clinical files were reviewed. Three neuropathologists evaluated the histological slides independently. Loss-of-heterozygosity analysis for 1p and 19q was performed by PCR. Favorable prognostic factors from univariate analyses included seizures as presenting symptom, female sex, location in the frontal lobe, low WHO grade, classic histology, absence of gemistocytic cells, and combined 1p/19q loss. Solitary 19q loss was a negative prognostic marker. 1p/19q status was of prognostic significance in both tumors with classic and nonclassic oligodendroglial histology. In the multivariate analysis, WHO grade II (P< .001), frontal tumor location (P= .002), and combined 1p/19q loss (P< .001) remained favorable prognostic variables. Our results suggest that tumor location, WHO grade, and 1p/19q status are important independent variables associated with survival in oligodendroglial tumors. The study suggests that solitary 19q loss is a negative prognostic variable and that 1p/19q loss is associated with prolonged survival also in oligodendroglial tumors without classic histology.

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.

Dysembryoplastic neuroepithelial tumor and oligodendroglioma: the diagnostic value of magnetic resonance spectroscopy. Case report and review of the literature

Preoperative differentiation between dysembryoplastic neuroepithelial tumor (DNT) and low-grade glioma is often not possible. Dysembryoplastic neuroepithelial tumor is a recently described entity of uncertain origin; however, the diagnosis has important clinical implications. Clinical and radiological findings of DNT and low-grade glioma, especially oligodendroglioma, may be similar. Treatment options and prognosis differ significantly between these two lesions; consequently, accurate diagnosis is imperative. The authors describe two individuals who presented simultaneously at their institution: one patient with an oligodendroglioma and a second patient with DNT. The natural history, neurodiagnostic, and pathological features of each are reviewed with special emphasis on the potential utility of magnetic resonance spectroscopy in differentiating these lesions.