The effect of thermochemotherapy with mitomycin C on normal bladder urothelium, an experimental study.

PURPOSE: To investigate the effects of thermochemotherapy with mitomycin C (MMC) on normal rabbit bladder urothelium and to compare it with standard intravesical MMC and hyperthermia with normal saline. METHODS: Twenty-four male New Zealand rabbits, with a mean weight of 2.7 kg (in weight of 2.1­4.3 kg), were divided into three groups, each containing eight rabbits. Thermotherapy with only normal saline was performed in the first group, standard intravesical MMC was performed in the second group, and thermotherapy with MMC was performed in the last group. A week after the primary procedure, total cystectomy was performed and tissue samples were evaluated. RESULTS: The presence of epithelial vacuolar degeneration (p = 0.001), epithelial hyperplasia (p = 0.000), subepithelial fibrosis (p = 0.001) and hemorrhagic areas in the connective tissue (p = 0.002) was observed statistically significantly higher in the standard MMC group than in thermotherapy with normal saline group. There was almost a significant difference among standard MMC and normal saline group in terms of vascular congestion in the connective tissue (p = 0.08). Presence of epithelial vacuolar degeneration (p = 0.002), epithelial hyperplasia (p = 0.002), subepithelial fibrosis (p = 0.030), hemorrhagic areas (p = 0.011) and vascular congestion (p = 0.36) in the connective tissue was observed statistically significantly higher in the thermochemotherapy with MMC group than in standard intravesical MMC group. Polymorphonuclear cell infiltration was not considerable in any of the groups, and there was no significant difference between each groups (p = 0.140). CONCLUSION: Administration of intravesical MMC causes a toxic effect on the normal urothelium of the bladder rather than an inflammatory reaction. Heating MMC significantly increased this effect.