New strategy of bio-chemoprevention on recurrence of superficial bladder cancer based on a hypothesis of the mechanism of recurrence.

There are theoretical limits to the efficacy of intravesical chemotherapy for prevention of tumor recurrence after transurethral resection of a superficial bladder cancer. Our multi-institutional studies revealed that the direct efficacy of BCG, intravesical instillation for treatment of an existing tumor is very promising. This efficacy persisted over a long period of time, and the subsequent recurrence rate was markedly reduced. Bladder cancer, sometimes earlier known as an occupational disease, might be related to unknown chemical carcinogens. Since enterobacterias are thought to produce carcinogens and mutagens, including nitroso-compounds in the intestinal tract, BLP (lactobacillus casei preparation), treatment may suppress the production of such compounds by altering the intestinal flora. Preclinical studies have demonstrated that BLP suppresses the development of bladder cancer induced by N-butyl-N-(4-hydroxy-butly)-nitrosamine in mice and rats. A double-blind clinical trial recently revealed that BLP was effective for preventing the recurrence of superficial bladder cancer. Bropirimine, a interferon inducer, is now an internationally developing agent for superficial bladder cancer, which is discussed on the basis of Japanese phase II trial data.