Variation of Estrogen and Progesterone Receptor Status in Breast Cancer after Tamoxifen Therapy

Abstract

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.

Effects of tamoxifen on normal breast tissue histological composition: Results from a randomised six‐arm placebo‐controlled trial in healthy women

“…We found that both low‐ and high‐dose tamoxifen reduced the expression of mammary epithelial ER by 5% to 8% in absolute percent difference, respectively, in premenopausal women. Our findings are in line with most previous studies investigating the effects of short‐term tamoxifen in breast tumours of predominantly premenopausal women showing that tamoxifen for up to 6 weeks at various doses significantly reduces the expression of ER in tumours or adjacent tissues 12,14,30‐34 . Our study is the first showing longer‐term effects up to 6 months of tamoxifen in the normal breast epithelium.…”

“…showing that tamoxifen for up to 6 weeks at various doses significantly reduces the expression of ER in tumours or adjacent tissues. 12,14,[30][31][32][33][34] Our study is the first showing longer-term effects up to 6 months of tamoxifen in the normal breast epithelium. In contrast to the association between reduced proliferation and epithelial area, we did not find any association between lower levels of epithelial ER and epithelial area change in women treated with tamoxifen.…”

Testosterone inhibits estrogen‐induced mammary epithelial proliferation and suppresses estrogen receptor expression

“…The present study shows a significant estrogen agonist effect by tamoxifen on primate mammary epithelial proliferation in vivo. Studies in human breast cancer cell lines have also shown that tamoxifen has ER-mediated proliferative effects (reviewed in ref 26). Whereas tamoxifen-induced mammary epithelial proliferation appears to be an estrogenic or ER agonist effect, tamoxifen has other effects on mammary epithelium that are opposite to those of estrogen and parallel to those of combined E2/T treatment ( Table 2).…”

Involvement of Long Non-Coding RNA HOTAIR in the Regulation of ERα36-Mediated Epithelial Mesenchymal Transition in Tamoxifen-Resistant Human Breast Cancer

“…One potential mechanism contributing to the development of antiestrogen resistance is the downregulation of ERα66 (Melchor et al 1990;Zhao et al 2011;Li et al 2013). To investigate the association between ERα66 gene expression and tamoxifen response, we analyzed a large cohort of ERα66-positive breast cancer patients from publicly available data (Gyorffy et al 2012).…”