Oral contraceptives, postmenopausal oestrogen-progestagen use and breast cancer.

Abstract

This article reports on clinical research on the relationship of female sex steroids to breast cancer carried out at Wilford Hall US Air Force Medical Center. A prospective study was initiated in 1975 to determine the incidence of breast and edometrial cancer in postmenopausal women using various hormone regimes, and records of patients with breast and endometrial cancer were identified retrospectively for the 1972-74 period. In addition, the records of the 461 women seen at the center for breast cancer in 1972-81 were analyzed. Of the 202 premenopausal women in the latter series, 133 (65.8%) had never taken any type of female sex steroid. Death has occurred in 39.8% of the nonsteroid users compared with 21.1% of the steroid users. The mortality rate was 68.6% in the nonusers with 4 or more positive axillary nodes compared to 50% in the oral contraceptive (OC) users of similar nodal status. None of the 13 hormone users with less than 4 positive nodes has died, wheras 18 of the 82 nonusers in this category died, suggesting that contraceptive steroids may have some beneficial biological effect on the breast. The incidence of mammary malignancy among current OC users in this series was 10.3/100,000 women/year. _in the prospective studyof postmenopausal hormone use, 53 cases of breast carcinoma were detected. Again, the incidence of breast cancer was lower in estrogen-treated women (141/100,000) than untreated women (342/100,000). The lowest incidence of breast cancer was observed among women who used preparations containing estrogen and progestagen (67.3/100,000), suggesting that progesterone deficiency may be an important factor in mammary malignancy. In light of the seeming protective effect of OCs, there is concern that adverse publicity generated by unsound epidemiologic studies may lead women to discontinue OC use, producing both an increase in breast cancer and unplanned pregnancies. Other benefits of OC use include decreased risk of endometrial cancer and less benign breast disease, ovarian cysts, and carcinoma