ACCUMULATION OF P53 AND KI-67 EXPRESSION DO NOT PREDICT SURVIVAL IN PATIENTS WITH FIBRILLARY ASTROCYTOMAS OR THE RESPONSE OF THESE TUMORS TO RADIOTHERAPY

OBJECTIVE: Although radiotherapy is often used in the treatment of pat ients with low-grade astrocytomas, its value is still uncertain. Radio therapy carries a risk of morbidity for patients and has time and cost implications for health services. We have assessed the value of two h istological variables, p53 accumulation and Ki-67 expression, in predi cting the response of astrocytomas to radiotherapy. The former antigen was assessed because many astrocytic tumors show mutations in the p53 gene, the function of which is crucial for mediating cell death after radiotherapy, and the latter was assessed because it is expressed onl y in proliferating tumor cells, which may show greater radiosensitivit y than nonproliferating cells. METHODS: Immunohistochemistry was used to detect the accumulation of p53 and expression of Ki-67 in a retrosp ective series of 96 patients with supratentorial fibrillary astrocytom as, 58 of whom had received postoperative radiotherapy. The immunohist ochemical data were correlated with survival after radiotherapy. RESUL TS: There was no significant difference in survival between the patien ts who did and those who did not receive radiotherapy. The p53 and Ki- 67 labeling indices did not correlate with survival in either the irra diated or the nonirradiated cohort, nor with overall survival in the s eries as a whole. CONCLUSION: Immunohistochemical assessment of p53 ac cumulation and Ki-67 expression does not help in predicting the surviv al of patients with supratentorial fibrillary astrocytomas or in predi cting whether particular patients are likely to benefit from radiother apy.