P53 IMMUNOHISTOCHEMICAL POSITIVITY AS A PROGNOSTIC MARKER IN INTRACRANIAL TUMORS

The frequency and scale of positive p53 immunohistochemistry in 107 intracranial tumours of different types was studied as a possible prognostic marker using a polyclonal antibody CM-I which detects both the wild-type and mutated p53 proteins. Fifty of the tumours (46.7%) showed nuclear p53 positivity with different percentages of positive nuclei. The positivity was concentrated in glial tumours of which 52.8% were positive. Forty-two of seventy-four astrocytomas (56.8%), 4 of 12 oligodendrogliomas (33.3%), and 1 of 3 ependymomas (33.3%) showed p53-positive nuclei. Cytoplasmic positivity, found in 25 astrocytomas, was always associated with nuclear positivity. Some p53-positive nuclei were seen in 16.7% of the non-gliomatous tumours, but in all cases p53 positivity was seen in less than 1% of the nuclei. The patients with astrocytomas containing more than 5% p53-positive nuclei were younger (mean 27.3 years) (p=0.016) and their tumours larger in diameter (mean 4.4 cm) (p=0.05) than those with p53-negative astrocytomas (mean 41.0 years and mean 3.3 cm, respectively). In p53-positive (greater than or equal to 1% of nuclei) grade IV astrocytomas, survival time was significantly shorter (mean 7.2 months) than in p53-negative grade IV astrocytomas (mean 15.5 months (p=0.024). The results indicate frequent p53 expression in intracranial tumours, especially in gliomas. The association of p53 positivity with young age, larger tumour size, and poor prognosis in high-grade astrocytomas suggests that p53 may be involved in the development of more aggressive types of intracranial tumours. According to these results, p53 immunohistochemical positivity may serve as a prognostic marker in high-grade astrocytomas.