RESUMO
To evaluate the prevalence of p53 gene expression and its role as a prognostic indicator in bladder carcinoma, we examined the paraffin-embedded tissue specimens from 43 patients with superficial and 31 patients with invasive bladder cancers. Nuclear expression of p53 proteins was detected by immunohistochemical analysis with microwave retrieve method, using the monoclonal antibody DO7 (Novocastra, UK). The p53 gene expression were divided into 4 categories (category 1: negative, category 2: 20%, diffuse, heterogeneous, weak intensity, category 4: >20%, diffuse, homogeneous, strong intensity). In total 74 cases, 67 (90.5%) showed positive (category 3 and 4) nuclear staining. Difference of nuclear expression between superficial and invasive cancer was not seen (96%, 84% respectively). But category 4 was more frequently seen in cases with invasive carcinoma compared to in superficial cancers (65% vs. 35%), and it was highly found in cases with grade 3 than grade 1 and 2 (79% vs. 27.5%) (p<0.005). Recurrence, progression, and survival in patients with superficial and invasive carcinoma between negative and weak intensity group (category 1,2,3) and strong intensity group (category 4) were not statistically significant. Our results showed higher positive rates than other studies may be due to using microwave retrieve method. These suggest that most bladder tumors have p53 mutations not only invasive but also superficial tumors and immunohistochemical stain using microwave retrieve method of bladder tumor specimens could be a good screening method for the presence of mutant p53 protein. The nuclear expression of p53 protein showed the trend of a stronger intensity in patients with invasive tumors and high histologic grade than in patients with superficial tumors and low histologic grade. These results also suggest that the degree of mutant p53 expression may be more useful for aggressive biological natures than the presence of mutant p53 protein.