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 anapl asia often show different biologic behaviour. Their uncommon occurrenc e 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 gl ioblastoma multiforme) and analysed the survival of patients with p53 immunoreactive versus non-reactive tumors. Of the cases examined, 8 we re 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 r eported for adult astrocytomas. The median survival in both p53-positi ve and p53-negative groups of pediatric malignant astrocytomas was sim ilar; however, the number of deaths in each group and the distribution of p53 scores is not statistically significant. Further studies to pr ecisely identify p53 and other genetic mutations in pediatric gliomas are needed to understand their biology and the rationale for therapeut ic options.