ABSTRACT
Background. p53 gene mutations are known to play an important role in the progression of bladder cancer. Immunohistochemistry (IHC) has been used routinely to analyze p53 gene mutations by identifying nuclear overexpression of p53 protein. However, the accuracy and value of IHC as a marker of p53 gene mutation has been questioned. Methods. In this study of 35 bladder transitional cell carcinoma, we compared results of IHC staining with those of polymerase chain reaction (PCR) of exons 5 to 8 of p53 gene, followed subcloning of PCR products, and DNA sequencing analysis. Results. On IHC staining, 12 bladder tumors (37.5%) showed overexpression of p53 as defined by nuclear staining of 10% or more of tumor cells. On DNA sequencing analysis, 11 out of 32 cases (34.3%) showed point mutations in one or more exons of p53 gene. The results of IHC were concordant with that of DNA sequencing in 84.3% of cases. The sensitivity and specificity of detecting p53 mutations by IHC were estimated to be 81.8% and 90.5%, respectively. Conclusion. When properly used, IHC is a highly sensitive and specific, and clinically useful method to detect p53 gene mutations in bladder cancer.