Long-term outcome of oligodendrogliomas

Favorable prognostic factors for oligodendroglial tumors include age younger than 40 years, low tumor grade, and extent of resection.

To assess survival time and prognostic factors of 100 patients with oligodendrogliomas diagnosed between 1995 and 2002.

The tumors were rated histologically by the WHO classification as low grade (grade II) or anaplastic (grade III). One hundred patients were categorized into three groups: group A: grade II, group B: secondary grade III (low grade with anaplastic transformation during the follow-up), group C: de novo grade III. All patients were symptomatic at presentation and underwent neurosurgical procedure for histologic diagnosis. Follow-up was performed with clinical assessment, brain MRI, and MIBI scintigraphy.

There were 66 men and 34 women (mean age at diagnosis 46.7 years). The most common first symptom was partial epileptic seizure (75%). Fifty-six patients had initial gadolinium enhancement (A: 15.6%; B: 36.8% as grade II, 95% as grade III; C: 90%), generally associated with MIBI hypermetabolism (p < 0.0001). Survival rates at 2, 5, and 10 years were A: 88%, 88%, 85%; B: 79%, 64%, 42%; C: 43%, 16%, 15%.

Secondary anaplastic oligodendroglioma patients were younger than patients with de novo anaplastic oligodendrogliomas. Histologic confirmation is mandatory because some low grade oligodendrogliomas had gadolinium enhancement on MRI and some anaplastic did not. Survival time was longer for secondary than for de novo anaplastic oligodendrogliomas without difference in the duration of the malignant phase of the disease.