Intravesical Bacillus Calmette-Guerin Therapy for Bladder Cancer: Molecular Mechanisms of Action

Over 40 years have passed since the discovery of its effectiveness in bladder cancer, and intravesical bacillus Calmette-Guerin (BCG) immunotherapy remains the mainstay for the treatment of non-muscle-invasive bladder cancer. Although efforts have been made to elucidate the mechanisms, those for BCG actions against bladder cancer are not fully understood. Nonetheless, it is now suggested that most of BCG effects are due to stimulation of immune system, leading to local host immune reactions and eventual cancer cell death. It is also likely that BCG has direct cytotoxic effects. The purpose of this review is to gather available data regarding the cascade of changes in urothelial cancer cells following exposure to BCG as well as to discuss the lacking information in the current literature.