Animal models of urinary bladder cancer and their application to novel drug discovery.

INTRODUCTION: Urinary bladder cancer is a major human malignancy that afflicts millions of people worldwide every year. Urinary bladder cancer is usually superficial at presentation in 70 - 80% of patients. In these cases, a simple transurethral resection is adequate for removing the tumor. However, some patients experience recurrence or even tumor progression. In another 20 - 30% of patients, muscle-invasive carcinoma is diagnosed. Despite all the developments in this area, even today, the options for treatment of urinary bladder cancer remain inadequate. The search for the mechanisms involved in human urinary bladder cancer and for new and improved treatment methods has led to the development of many experimental models using laboratory animals over the past 40 years. AREAS COVERED: In this review, the authors provide a concise overview of the animal models used to study urinary bladder cancer. Furthermore, the authors discuss their advantages and disadvantages with regard to the search for new therapeutic approaches. EXPERT OPINION: The use of urinary bladder cancer models for understanding the mechanisms involved in tumors' response to new treatments is an important step in the drug discovery process. However, the authors believe that it will be necessary to develop our knowledge and understanding of the molecular processes underlying urothelial chemical carcinogenesis for us to better evaluate the efficacy of novel therapeutics.