p53 protein in pediatric malignant astrocytomas: a study of 21 patients.

Malignant astrocytomas are uncommon brain tumors in children and it is known that astrocytic tumors with similar degrees of histologic anaplasia often show different biologic behaviour. Their uncommon occurrence has resulted in relatively few studies of the molecular biology and genetics of pediatric malignant astrocytomas with somewhat conflicting results, in contrast with the many studies addressing astrocytomas in adults. p53 immunoreactivity has been used to screen tissues for the abnormal presence of the p53 protein and abnormal immunoreactivity has been demonstrated in one-half to two-thirds of adult astrocytomas. We studied the frequency of p53 immunoreactivity and gene alteration in 21 children with malignant astrocytomas (anaplastic astrocytoma and glioblastoma multiforme) and analysed the survival of patients with p53 immunoreactive versus non-reactive tumors. Of the cases examined, 8 were anaplastic astrocytoma (AA) and 13 were glioblastoma multiforme (GM). We found that the overall frequency of p53 immunoreactivity of 47% in this group of pediatric malignant astrocytomas is similar to that reported for adult astrocytomas. The median survival in both p53-positive and p53-negative groups of pediatric malignant astrocytomas was similar: however, the number of deaths in each group and the distribution of p53 scores is not statistically significant. Further studies to precisely identify p53 and other genetic mutations in pediatric gliomas are needed to understand their biology and the rationale for therapeutic options.