Experimental induction of uterine adenocarcinoma in rats by estrogen and N-methyl-N-nitrosourea.

To induce uterine endometrial adenocarcinoma, Donryu rats were given subcutaneous injections of 100 micrograms/kg estradiol dipropionate (ED) four times once a week from 3 months old, followed by weekly intraperitoneal injections of 20 mg/kg N-methyl-N-nitrosourea (MNU) four times. In the ED+MNU group, the incidences of marked hyperplasias and adenocarcinomas were higher than those in the control and ED or MNU alone groups, when the incidences were compared in survival cases only up to the age of about 15 months, while the survival rate showed a specially low value of 35% in this group. These results may suggest the possibility of early and high occurrence of uterine adenocarcinoma in this rat strain by estrogen and MNU.