Variation of estrogen and progesterone receptor status in breast cancer after tamoxifen therapy

In the present paper we have studied the quantitative variations in estrogen (ER) and progesterone receptor (PR) content of breast cancer induced by tamoxifen. In addition to receptors, hormonal levels of estradiol, progesterone, prolactin, FSH, LH and testosterone were also measured. The cases included in our study were consecutively selected among those breast cancers in which an aliquot of the tissue sample sent for analysis of the steroid receptors was positive for cancer and also found to have at least one of the steroid receptors positive, not only in the biopsy but also in the surgical specimen. Following this criterion, we finally collected 14 cases of breast cancer treated daily with 30 mg of tamoxifen during an interval of 3 weeks from the initial biopsy to the final surgery. From our results we can conclude that tamoxifen reduced significantly the ER concentration while no changes were observed in PR values. Concerning hormones, while in premenopausal patients tamoxifen induced a rise in plasma estradiol, in postmenopausal women the only modification observed was a decrease in plasma FSH. The variation in steroid receptor content under tamoxifen therapy may also contribute to the evaluation of the hormone dependency of gynecologic malignancies.