Promoting the effects of intravesical instillation of saline on bladder lesion development in rats pre-treated with BBN

BACKGROUND: At present, immunotherapeutic agents such as bacillus Calmette-Guerin (BCG) and anti-tumor chemotherapeutic agents in saline are used intravesically in patients with bladder carcinoma. However, of greater significance is the possibility that the saline vehicle may itself promote carcinoma development in the bladder. METHODS: The potential promoting effects of intravesical instillation of saline were assessed in female F344 rats. The animals were divided into 3 groups, all of which received 0.05% N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) in their drinking water for the first 10 weeks. They were then maintained without further treatment (group 1) or received intravesical instillations of 0.3 mL of saline or distilled water once a week for 6 weeks, 15 weeks after the end of the BBN treatment (groups 2 and 3). At 32 weeks, all the animals were killed and examined immunohistochemically with proliferating cell nuclear antigen (PCNA) antibody, as well as by routine histopathologic examination. RESULTS: Both the incidence and the number of bladder carcinomas were higher in the animals that received instillations of saline than in those who did not receive the instillations. Significant increases in tumor size were also noted for the saline-treated groups, although this was not linked with the PCNA labeling index. CONCLUSIONS: The results indicate that saline is a promoter of urinary bladder carcinogenesis either because of the catheterization or the fluid itself.