Modulatory influences of exogenous estrogen on MCA-induced carcinogenesis in the uterine cervix of mouse.

Placement of cotton-thread impregnated with beeswax containing methylcholanthrene (approx. 600 micrograms) inside the canal of uterine cervix of virgin adult mice results in the emergence of precancerous and cancerous lesions in the cervical epithelium. Employing this experimental cervical carcinogenesis model system, the present study evaluates the modulatory influence of exogenous 17 beta-estradiol on the incidences of precancerous and cancerous lesions in the cervical epithelium. When 17 beta-estradiol was administered weekly at the dose levels of 0.01 microgram, 0.1 microgram, 5 micrograms and 50 micrograms for 16 weeks following carcinogen-thread insertion, the cervical carcinoma incidences, as compared to that in positive control mice (76.1%), were 66.6%, 61.5%, 55.5% and 42.1%, respectively. The decline in the incidence of carcinomas at 50 micrograms/week dose level was significant (P less than 0.05). Hyperplastic and dysplastic changes did not show any definite correlation with the various treatments.