Bladder carcinogenesis in mice induced by N-butyl-N-(4-hydroxybutyl) nitrosamine and N-ethyl-N-(4-hydroxybutyl)-nitrosamine with reference to the effect of cyclophosphamide.

The carcinogenicities of N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN) and N-ethyl-N-(4-hydroxybutyl) nitrosamine (EHBN) on the urinary bladder were compared in male BALB/c mice. The effect of cyclophosphamide (CPA) on the carcinogenicities was also investigated. The carcinogenic activity on the bladder mucosa of EHBN was similar to that of BBN, and there was no difference in the growth patterns, histological types or invasive characters of carcinomas induced by BBN and EHBN. Benign or malignant tumors of vascular origin developed in the urinary bladders of 15 mice treated with these carcinogens. The incidence of vascular tumors induced by EHBN was significantly higher than that of tumors induced by BBN. Intraperitoneal injections of CPA seemed to have no effect in the incidence of bladder carcinomas induced by these carcinogens, or on the development of vascular tumors in the bladder wall induced by EHBN.