PROGNOSTIC INDICATORS IN A RANGE OF ASTROCYTIC TUMORS - AN IMMUNOHISTOCHEMICAL STUDY WITH KI-67 AND P53 ANTIBODIES

The treatment and prognosis of patients with cerebral astrocytic tumou rs are currently guided by histopathological classification. This stud y evaluates immunohistochemistry using Ki-67, an antibody to a nuclear protein expressed in proliferating cells, and DO-7, an antibody to th e product of the tumour suppressor gene p53, as prognostic indicators for these tumours. Immunohistochemistry with Ki-67 has been correlated with the behaviour of many different tumours, but its value as a prog nostic indicator in astrocytic tumours is diminished by the conflictin g results of previous studies. Immunehistochemistry with antibodies to the p53 protein has been used as a prognostic indicator in melanomas and some carcinomas, but the relation between prognosis and accumulati on of this protein in astrocytic tumours has not been clarified. We ha ve tested the hypothesis that survival is correlated with Ki-67 immuno labelling indices (LIs) and patterns of p53 immunolabelling in the cer ebral astrocytic tumours of a large cohort of patients (n = 123) for w hom clinical indices were well documented. Astrocytic tumours were div ided into three histological types: fibrillary astrocytoma (n = 24), a naplastic astrocytoma (n = 31), and glioblastoma (n = 68). Histologica l type and patient age were independent predictors of survival. Median Ki-67 LIs differed significantly (P < 0.0001) between the types of as trocytic tumour, and tumours with a Ki-67 LI < 2% had a significantly (P < 0.0001) better prognosis. Ki-67 LI as a continuous variable carri ed a significant (P = 0.0043) unadjusted hazard to survival which was lost when adjusted for other variables, notably histological type. By contrast, no relation was found between survival and three categories of p53 labelling (p53-negative, p53 LI < 40%, and p53 LI > 60%). The r esults indicate that, whereas Ki-67 immunohistochemistry predicts surv ival in patients with astrocytic tumours, conventional histological ap praisal remains the best guide to prognosis, and immunehistochemistry for p53 has no value in the assessment of these tumours.