Purpose: To identify subgroups in glioblastoma multiforme (GBM) with different susceptibilities to radio-chemotherapy by p53 protein and Ki-67 expression.

Patients and Methods: Thirty-one patients with primary GBM underwent a combined radio-chemotherapy with topotecan. Percentage of cells expressing p53 protein and Ki-67 antigen was determined immunohistochemically. Additionally, the cell density within the tumour tissue was measured.

Results: Median percentages of p53 and Ki-67 expressing cells were 4.3% (range = 0–28%) and 12.0% (range = 0–28%), respectively. Dividing the cases into two groups by high or low p53 protein 1-year disease-free survival rates were 13.3% and 23.6%. High or low Ki-67 expression showed one-year disease-free survival rates of 18.8% and 17.1%. Neither p53 nor Ki-67 expression showed a significant correlation with disease-free survival or overall survival. Median cell density was 252 cells/field (range = 42–595). 1-year disease-free survival rates were 14.5% and 21.7% in high and low cell density group, respectively. A significant correlation with progression-free survival was observed, whereas the stratification into two groups revealed no significance. Cell density showed a significant inverse correlation with p53 and Ki-67 immunopositivity.

Conclusion:p53 protein and Ki-67 expression seem to be inappropriate for the estimation of prognosis in patients receiving a combined radio-chemotherapy with topotecan.