Experimental bladder tumor induction, propagation, and therapy.

The development of animal bladder tumor models as a research tool for different modes of therapy has been widely evaluated. Recently these tumors have either spontaneously grown or have been propagated in inbred strains. Bladder tumors have also been chemically produced by N-[4-(5-nitro-2-furyl)-2-thiazolyl] formamide (FANFT) when orally administered over a long period of time. It has been further reported that these tumors have been inhibited by various chemotherapy regimens. The availability of an experimental bladder tumor model offers an opportunity to evaluate the effectiveness of a prescribed treatment. In our studies FANFT was noted to produce only from 33 to 40% bladder tumors in several experiments in an inbred strain of rats conducted over several years. Reproducible transplantability of these tumors was not demonstrable in the same inbred strain. In addition, treatment with mitomycin C an an effective chemotherapeutic agent was not detectable in part, since comparably the percentage of control bladder tumor growth was low. These findings of a three-year study should be carefully considered when evaluating recommendations for clinical adjuvant chemotherapy based on results obtained with FANFT.