Prognostic and survival-related factors in patients with well-differentiated oligodendrogliomas

Oligodendrogliomas are brain tumors with unpredictable biological and clinical behavior. Prognostic factors related to survival are still controversial. The present study reviews 50 patients with well-differentiated (WHO grade II) oligodendrogliomas, located in the cerebral hemispheres and operated upon between 1980 and 1998. Prognostic factors studied include patient's age and sex, tumor location and extent, preoperative KPS, and extent of the surgical resection. The Ki-67 and the proliferative cell nuclear antigen (PCNA) levels were studied in all patients and some growth factors (GFs), including vascular endothelial growth factor (VEGF), epidermal growth factor (EGF), platelet-derived growth factor (PDGF) and tenascine were examined in 20 patients. The long-term outcome and survival are not significantly correlated with the patient's age and sex, tumor location and extent, preoperative KPS and procedure for resection. Patients with lower Ki-67 and PCNA showed a significantly longer survival time (p < 0.001 and p < 0.019, respectively). Between 45 and 70 % of the tumors stained positive for one or more growth factors. Interestingly, cases with late recurrences (more than 4 years after surgery) and longer survival are significantly associated to negative GF expression or slight positivity, as compared with the variable and more often moderate immunoreactivity of cases with early anaplastic recurrences and shorter survival time. The presented data suggest that low proliferation indices and negative GF expression are associated with longer survival in well-differentiated oligodendrogliomas.