Clonal analysis of human recurrent superficial bladder cancer by immunohistochemistry of p53 and retinoblastoma proteins

Purpose: To investigate the clonal origin of malignant cells in recurrent superficial bladder cancer. Materials and Methods: We compared the protein expression of p53 and retinoblastoma (Rb) by immunohistochemistry using antibody P1801 and PMG3-245, respectively, in 13 patients at the time of primary superficial bladder cancer resection (6 Ta and 7 Tl) and their 15 corresponding recurrences of disease, Mutations in p53 and Rb is ere inferred on the basis of immunoperoxidase staining. Results: At the time of initial tumor resection, a p53 mutation was observed in 5 patients (39%) and an Rb mutation was observed in 3 (23%). The p53/Rb mutation status of recurrent bladder cancers completely matched their corresponding primary bladder cancer. Conclusions: The chance that recurrent bladder cancer originated from independent clones in this study was extremely small (p < 10(-6)). This result strongly supports the monoclonal origin of recurrent superficial bladder cancer.