OBJECTIVE: To examine the correlation between partial bladder outlet obstruction (PBOO) and bladder carcinogenesis. MATERIALS AND METHODS: Female Wistar rats (6 weeks old) were divided into three groups of 10 each: group 1 was exposed to n-butyl-n-butanol nitrosamine (BBN, a carcinogen) in drinking water for 8 weeks; group 2 had PBOO induced surgically after exposure to BBN for 8 weeks; group 3 had a sham operation and the rats drank normal water (control group). After 20 weeks, all of the rats were killed humanely and their bladders analysed. RESULTS: There were no significant differences in body weight among the groups. The bladder weight of group 2 was significantly greater than either group 1 or group 3. Histopathologically, bladder smooth muscle hypertrophy was the major cause of the increased bladder weight for group 2. In group 2 there were increases in bladder wall thickness and many nipple-shaped urothelial tumours. Basic fibroblast growth factor and hypoxia-inducible factor-1alpha expression were significantly greater in group 2 than in groups 1 and 3. CONCLUSIONS: Exposure of the bladder to carcinogens during bladder hyperplasia and hypertrophy induced by PBOO results in a greater incidence of superficial bladder carcinoma.
OBJECTIVE: To examine the correlation between partial bladder outlet obstruction (PBOO) and bladder carcinogenesis. MATERIALS AND METHODS: Female Wistar rats (6 weeks old) were divided into three groups of 10 each: group 1 was exposed to n-butyl-n-butanol nitrosamine (BBN, a carcinogen) in drinking water for 8 weeks; group 2 had PBOO induced surgically after exposure to BBN for 8 weeks; group 3 had a sham operation and the rats drank normal water (control group). After 20 weeks, all of the rats were killed humanely and their bladders analysed. RESULTS: There were no significant differences in body weight among the groups. The bladder weight of group 2 was significantly greater than either group 1 or group 3. Histopathologically, bladder smooth muscle hypertrophy was the major cause of the increased bladder weight for group 2. In group 2 there were increases in bladder wall thickness and many nipple-shaped urothelial tumours. Basic fibroblast growth factor and hypoxia-inducible factor-1alpha expression were significantly greater in group 2 than in groups 1 and 3. CONCLUSIONS: Exposure of the bladder to carcinogens during bladder hyperplasia and hypertrophy induced by PBOO results in a greater incidence of superficial bladder carcinoma.