Recurrent astrocytic tumours — a study of p53 immunoreactivity and malignant progression

Recurrence and progression to higher grade lesions are characteristic of the clinical course of astrocytic tumours. Though p53 gene mutation is an impor tant initiating event in astrocytic tumourigenesis, its role in malignant progression remains controversial. We have therefore analysed p53 protein expression in paired histological samples from 48 cases of astrocytic tumours and their recurrences - 29 diffuse astrocytoma, 10 anaplastic astrocytoma and 14 glioblastoma multiforme (GBM). Malignant progression at recurrence was noted in 93% of diffuse and 64% of anaplastic astrocytomas. An association was observed of p53 protein immunopositivity and malignant progression at recurrence. Thus, 27 of 48 (56%) primary tumours were initially p53 positive, while in recurrent tumours associated with malignant progression this frequency increased to 71% (34/48 cases). This was because seven of the 13 cases (4/8 diffuse and 3/5 anaplastic astrocytoma) that were initially p53 negative acquired immunopositivity on mali...