Prognostic value of Mdm2, p53 and p16 in patients with astrocytomas

Surgical cure of gliomas infiltrating into the brain is practically impossible and their clinical course is primarily determined by the biological behavior of the tumor cell. The purpose of this study was to analyze retrospectively prognostic input of p53, Mouse double minute-2 (Mdm2) and p16 in 103 uniformly treated patients with astrocytic tumors. The expression of these molecules was measured by immunohistochemical procedure. Prognostic evaluation was performed with the multivariate proportional hazards model. The follow-up period lasted 19 (5-122) months for the survivors. We observed that 66% of gliomas showed mutated p53, while only 17% overexpressed Mdm2, the p53-regulatory molecule. Besides, almost 50% of gliomas lost p16 immunopositivity. Only p53 labeling showed a positive correlation with the grade of malignancy, according with the WHO classification. The association between mutated p53 and histological grade remained when prognostic variables were considered in a multivariate analysis. No association between p53 status and overall survival was found. On the other hand, Mdm2 overexpression and, unexpectedly, p16 immunopositivity were associated with a shorter survival in an univariate analysis. However, Cox-regression analysis showed that only Mdm2 in female patients was an independent prognostic factor, associated with shorter survival. In conclusion, our results suggest that Mdm2 could be a relevant marker in determining the evolution of glioma patients and could provide a more objective way to classify astrocytomas.