Oral contraceptives: relations to mammary cancer, benign breast lesions, and cervical cancer.

The results of experimental studies on the relationship of estrogens and oral contraceptives to mammary lesions demonstrate that the type of response obtained depends largely on the species and strain of animal that is employed. A variety of clinical studies has failed to demonstrate that estrogen can cause mammary cancer, this lack of effort correlates with the results obtained in various studies in animals. Similar relationships exist for oral contraceptives, and the clinical data show good agreement in demonstrating that the contraceptive steroids do not have a tumorigenic effect on the human mammary gland. Estrogen can increase the occurrence of cervical cancer in certain strains of mice, but apparently this effect is not observed in other species of animals, including man. The preponderance of data shows that oral contraceptives do not adversely affect the occurence of abnormal Papanicolaou smears, cervical dysplasia, cervical cancer in situ, or invasive cervical cancer.