ESTRADIOL AND PROGESTERONE RECEPTOR LEVELS IN HUMAN BREAST ADENOCARCINOMA IN RELATION TO PLASMA ESTROGEN AND PROGESTERONE LEVELS

  • 1 January 1978
    • journal article
    • research article
    • Vol. 38  (10) , 3468-3473
Abstract
Plasma estrogen and progesterone levels were determined in 77 premenopausal and 137 menopausal women at the same time that estradiol receptor (ER) and progesterone receptor (PGR) assays were done on their breast cancers. The frequency of ER and PGR is approximately the same in premenopausal and postmenopausal women, but the ER contents is higher in postmenopausal women. Although this is usually ascribed to the occupancy of receptors of endogenous estrogen in premenopausal women, these observations suggest that this is unlikely. The high ER content in postmenopausal women is probably due to the fact that the cyclic progesterone increase in premenopausal women limits estrogen stimulations of ER synthesis. The circulating levels of estrogen in postmenopausal women are sufficient to stimulate ER and PGR when ER is functional. In premenopausal women, high levels of circulating progesterone may inhibit PGR, and the absence of PGR in the breast cancers of premenopausal women should be interpreted warily if the plasma level of progesterone is unknown.