Abstract
Since its introduction by Morales et al. in 1976, intravesical Mycobacterium bovis bacillus Calmette-Guerin (BCG) has served as a key, adjuvant therapy in the treatment of non-muscle invasive bladder cancer. Despite decades of use, the exact mechanism of action of BCG remains unclear; nevertheless, multiple studies have continued to document its efficacy in the treatment of non-muscle invasive bladder cancer. Mechanistic investigations have elucidated many processes of the immunotherapeutic pathways responsible, but our understanding needs to be further studied to establish a more efficient means to decrease recurrence and progression. In the USA alone, urologists prefer the use of BCG to intravesical chemotherapy to a ratio of 2:1. Furthermore, the American Urologic Association, in its most recent published guidelines on the management of non-muscle invasive bladder cancer, has recommended BCG be the first-line treatment for carcinoma in situ because of its proven track record. BCG, a live-attenuated strain of bacteria, is fraught with potential adverse reactions; the weight of treatment success must be carefully balanced against any possible harm to prospective patients. In conjunction with TUR, adjuvant use of BCG will continue to be utilized as more definitive guidelines are created with minimal dose therapy and reduction in side effect profile. This chapter will discuss current mechanistic understanding of BCG immunotherapy, possible markers of BCG treatment prognosis, and the clinical applications for the treatment of initial and recurrent non-muscle invasive bladder cancer.