Effects of pre- and postmenopausal use of exogenous hormones on receptor content in normal human breast tissue: A randomized study

Abstract

Objective. To examine the effects of exposure to endogenous and exogenous hormones on estrogen receptor-α (ERα) and progesterone receptor (PR) levels in normal human breast tissue.Methods. In a randomized study of women scheduled for mammary reduction plasty (n = 81), ERα and PR content in breast parenchyma was analyzed in premenopausal (n = 49) and postmenopausal (n = 16) women. Premenopausal women were randomized to surgery in the follicular or luteal phase of the menstrual cycle or after oral contraceptive treatment for 2 months. Postmenopausal women were randomized to sequential or estrogen-only therapy for 2 months prior to surgery.Results. ERα content was higher in parous than in nulliparous (p = 0.009) premenopausal women and displayed a positive association with age (rs = 0.51, p = 0.0002). Compared with premenopausal women in the follicular phase, postmenopausal women had higher ERα content (p = 0.040) whereas premenopausal women on oral contraception had lower ERα (p = 0.048) and PR (p = 0.007) content. Smokers had lower PR content than non-smokers (p = 0.02).Conclusion. In the present study ERα content was higher in parous than in non-parous women and associated with premenopausal age. Short-term oral contraceptives yielded lower ERα and PR contents. Postmenopausal estrogen/progestogen combined therapy yielded lower PR content than estrogen-only therapy.