Determination of tamoxifen and its metabolites in the endometrial tissue of long-term treated women

Concentrations of tamoxifen and its metabolites were analysed in the endome trium of 23 post-menopausal asymptomatic breast cancer patients who were on chronic tamoxifen therapy. Small endometrial samples were collected during diagnostic hysteroscopy. Analysis of both serum and tissue for these compo unds was performed by mass spectrometry. Tamoxifen and its metabolites were far more concentrated in the endometrium than in serum; tamoxifen was also significantly more concentrated in endometrium with hyperplastic changes t han in atrophic endometrium. Endometrial polyps of an additional 9 women sh owed a trend to a lesser concentration of compounds. Increased concentratio n of tamoxifen compounds could possibly be explained by the avidity of thes e compounds for oestrogen receptors (ER). (C) 2000 Elsevier Science Ltd. Al l rights reserved.