Neoplasia of the female reproductive tract: effects of hormone therapy.

This review presents the data on the relationship between estrogen and estrogen plus progestin therapy in postmenopausal women and the occurrence of neoplasia in the endometrium, ovary, and uterine cervix. Estrogen only in women with an intact uterus consistently is shown to increase the incidence of endometrial cancer. Estrogen plus a cyclic or sequential progestin reduces the incidence of endometrial cancer to that found in never users. The duration of the progestin administration appears to be important with less than 10 d of progestin having an increased incidence of cancer after 5 yr of therapy. Continuous estrogen plus progestin does not increase the incidence of endometrial cancer. Estrogen and estrogen plus progestin effects on the occurrence of ovarian cancer are inconsistent. The data suggest a possible increase in ovarian epithelial tumors with >10 years use of estrogen only. There is no evidence of a change in the incidence of uterine cervical neoplasia with either estrogen or progestin.