Direct action of estradiol on benign human breast tumors

Estrogens have been known to enhance the development and growth of mammary carcinoma in a variety of experimental animals. These steroids have been considered potentially oncogenic factors in human breast cancer. Organ culture techniques have been used to study the role of the complex hormonal interrelationship existing in vivo and to evaluate and compare the direct effects of hormones on tissue growth. The object of this study was to determine the effect of 17B-estradiol (E) on DNA synthesis of benign human breast tumors in 5 day organ cultures. Tissues obtained from 23 patients were processed into explants and each tumor was individually cultured at 37°C (95% 0₂, 5% CO₂) in Medium 199. All media contained penicillin G (50 I.U./ml), hydrocortisone (1.0 μg/ml) and insulin (5.0 μg/ml). Each biopsy specimen was divided into 2 groups: Group I as a control and Group II received E (1.0 μg/ml). When E was added to the synthetic media containing explants of benign breast tumors a significant increase (P < 0.05) in labelled-thymidine incorporation into DNA was observed in comparison to controls. The most important feature of this study was the demonstration that these tumors respond directly to the effect of estrogen, as indicated by increased DNA synthesis after 5 days of culture.