Role of estrogens and progesterone in the etiology and prevention of endometrial cancer: review.

Our present knowledge of the role of sex steroids in the development as well as the prevention of endometrial cancer is reviewed. Factors which increase the exposure of the uterus to unopposed estrogens, either exogenous or endogenous, are associated with increased risk of endometrial adenocarcinoma. However, there is increasing evidence that progestogens can reverse endometrial hyperplasia and protect against the development of endometrial cancer. The mechanisms to explain the antiestrogenic effects of progestogens include changes in enzyme activity and steroid receptors in endometrial tissue. Postmenopausal women treated with combined estrogen and progestogen have the lowest incidence of endometrial carcinoma. Oral contraceptives containing both estrogen and progestogen in each tablet are protective against adenocarcinoma of the endometrium, while the sequential oral contraceptive pills afforded less protection. The risks and benefits of these hormone therapies are discussed in relation to the etiology and prevention of endometrial cancer.