P53 IMMUNOREACTIVITY IN ASTROCYTOMAS AND ITS RELATIONSHIP TO SURVIVAL

p53 is a putative tumour suppressor gene implicated in a wide range of human malignancies. Mutation of p53 gene results in a more stable pro duct and increased quantities of p53 protein in the cell. Thus, unlike the normal situation, mutated p53 is detectable by immunohistochemist ry. We stained frozen sections of 74 astrocytomas with two antibodies to p53, PAb 1801 and PAb 421. Overall 18/74 (24%) of astrocytomas show ed p53 immunoreactivity. Fifteen of 47 (32%) grade IV were p53 immunop ositive, as were 3/16 (19%) grade III, 0/7 (0%) grade II and 0/4 (0%) grade I astrocytomas. These findings are in agreement with previous st udies in showing relatively greater numbers of high grade than low gra de p53 immunopositive rumours. Although we found an expected differenc e in survival according to grade, there was no significant difference in survival (p > 0.1) between p53 immunopositive and immunonegative ru mours. We conclude that, whilst p53 undoubtedly plays an important rol e in the molecular 'chain' leading to malignancy in some astrocytomas, within rumours of comparable grade it does not appear to influence su rvival.