The difference of prognosis in patients with the same WHO grade of astrocytic tumors suggests that such tumors comprise a heterogeneous group in biological behavior. The correlation between p53 immunoreactivity and prognosis has often been reported but remains controversial. From the perspective of clonal expansion of p53 immunopositive cells, the distribution patterns of p53 immunoreactivity can be divided into four types: negative, scattered, focally clustered, and diffusely clustered. The survival rate was evaluated by classifying the p53 immunoreactivity into two groups: the significantly immunopositive patterns (focally and diffusely clustered types) and the significantly immunonegative patterns (negative and scattered types). The survival analysis showed a highly significant difference between these two patterns within the same WHO grade of astrocytic tumors (p = 0.0185). Our studies demonstrate that the distribution patterns of p53 immunoreactivity, which reflect the trends of clonal expansion of p53 immunopositive cells, are significantly valuable in predicting the prognosis of patients with the same WHO grade of astrocytic tumors.