Antitumor Effect of Bacillus Calmette-Guérin in Bladder Cancer

Bacillus Calmette-Guérin (BCG) is currently the standard therapy for treating high grade non-invasive bladder cancer. BCG is superior to intravesical chemotherapy. The antitumor effect of BCG seems to be related to cellular immunological mechanisms. However, its precise mode of action is unknown. High-risk non-invasive bladder tumors in patients will progress to muscle-invasive bladder cancer despite BCG treatment. Traditional prognostic factors are mainly based on histopathological characteristics. However, there are no clear definitive markers for the response to therapy, partly because of a lack of knowledge concerning the mechanism of action utilized by BCG to mediate the observed clinical response. In response to the inflammatory process, the urothelial and tumor cells upregulate the expression of important surface proteins, such as major histocompatibility antigens, adhesion molecules, and death receptors. These proteins might serve as markers and potential therapeutic targets to enhance BCG efficacy. The genetic and molecular changes that occur in transitional cell carcinoma (TCC) of the bladder are numerous. Recent advances in carcinogenesis research will permit the discovery of new markers in patients treated with BCG that are directly involved in the pathogenesis of bladder cancer. Further investigations of the antitumor effect of intravesical BCG will lead not only to a potential enhancement of the BCG response, but probably also to a better understanding of bladder carcinogenesis.