Urine analysis data obtained using modern microbiological methods and 16S rRNA gene sequencing technology indicate that the urinary system has its own microbial ecosystem. Individual microbiota members can play a key role in the development of cancer. Certain bacterial taxa have been revealed in bladder urothelial carcinoma cells that can affect carcinogenesis, treatment response, and the development of relapses through various mechanisms. The studies are conducted to use not only vaccine strains, but also probiotic strains and oncolytic bacteria for the treatment and prevention of relapses.