Treatment of newly diagnosed symptomatic pure low-grade oligodendrogliomas with PCV chemotherapy.

Based on studies relating to anaplastic oligodendroglioma (OG) chemosensitivity and benefit of time to progression or overall survival, chemotherapy for pure OG has been proposed. Several studies have reported the efficacy of various chemotherapeutic agents in a small number of patients with low-grade gliomas, e.g. pure astrocytomas, OG or mixed histologies. The 5-year survival rate varies from 61% to 89% with a mean time to progression of 5 years. We report the outcome of 33 consecutive patients with pure low-grade OG diagnosed between 1990 and 2006 systematically treated for residual or non-removable tumor with PCV chemotherapy regimen as the front-line treatment after surgery. All the tumors were low grade (grade II) pure OG according to the WHO classification. All patients were symptomatic at presentation and underwent neurosurgical procedure for histological diagnosis. Response was evaluated by clinical assessment and brain magnetic resonance imaging. Twenty-one men and 12 women with a mean age at pathological diagnosis of 46.5 years were studied. The most common first symptom was partial epileptic seizure (73.7%). Six patients (18%) had initial gadolinium enhancement, associated with methoxyisobutyl (MIBI) hypermetabolism (P < 0.001). The resection was partial in seven cases (21%), and 26 patients (79%) had biopsy only. Eleven patients (36%) had a malignant transformation during the follow-up with a median time to progression of 19 months. Favorable prognostic factors were lack of contrast enhancement (P < 0.0001), and age <40 years (P < 0.0003); 90% of patients were progression-free at 1 year. Survival rates at 2, 5 and 10 years were 85%, 75% and 50%, respectively. Up-front chemotherapy with PCV regimen is a good treatment for symptomatic pure low-grade OG, as it increases the number of progression-free patients and time to progression. These results suggest that radiotherapy could be postponed until the malignant transformation occurs to delay cognitive side effects of irradiation.