EPIDEMIOLOGIC CONSIDERATIONS ON THE SIGNIFICANCE OF HORMONES IN CARCINOGENESIS

The incidence of gynecologic malignancies shows considerable regional differences which suggest a decisive role of environmental and endocri ne factors in tumor genesis. The risk of developing breast cancer incr eases with increasing age, a positive family history, prolonged exposu re to estrogens (early menarche, late menopause), nulliparity, alcohol consumption, and obesity. A relationship between a long exposure to e strogens and an increased risk of cancer may also be assumed in the ca se of endometrial cancer. Whether estrogens or their metabolites promo te the initiation of cancer remains to be clarified. Endocrine monothe rapy with only an estrogen, obesity, nulliparity/infertility as well a s a late natural menopause are well-known risk factors of developing e ndometrial cancer. Whereas estrogens induce a hyperplasia of the endom etrial mucosa, gestagens exert a protective effect on the endometrium. Old age, a family history of breast, endometrial and ovarian cancer a s well as persistent or treated infertility are the established risk f actors of ovarian cancer. Each pregnancy, the intake of oral contracep tives, a hysterectomy or tubal ligation are associated with a decrease d risk of developing ovarian cancer; hormonal replacement therapy has no influence on the risk of ovarian cancer.