PT  - JOURNAL ARTICLE
AU  - M J E Mourits
AU  - K A Ten Hoor
AU  - A G J van der Zee
AU  - P H B Willemse
AU  - E G E de Vries
AU  - H Hollema
TI  - The effects of tamoxifen on proliferation and steroid receptor expression in postmenopausal endometrium
DP  - 2002 Jul 01
TA  - Journal of Clinical Pathology
PG  - 514--519
VI  - 55
IP  - 7
4099  - http://jcp.bmj.com/content/55/7/514.short
4100  - http://jcp.bmj.com/content/55/7/514.full
SO  - J Clin Pathol2002 Jul 01; 55
AB  - Aim: To study the effects of tamoxifen on the proliferation index and oestrogen receptor (ER) and progesterone receptor (PR) expression in postmenopausal endometrium. Methods: A total of 125 endometrial specimens of postmenopausal women, comprising benign endometria from tamoxifen users (n = 35) and non-users (n = 24), and endometrial cancer from tamoxifen users (n = 15) and non-users (n = 51), were immunohistochemically examined using MIB-1, anti-ER, and anti-PR antibodies in endometrial epithelium and stroma. Results: In benign endometrium the mean MIB-1 index in the epithelium was higher in tamoxifen users than in non-users (mean, 13% (SD, 13%) v mean, 2% (SD, 2%); p < 0.05), whereas in endometrial cancer the MIB-1 index was higher, but similar in tamoxifen users and non-users (mean, 32% (SD, 24%) and mean, 35% (SD, 18%)). The expression of ER was comparably high in benign epithelium from tamoxifen users and non-users (97% and 92%, respectively), but in endometrial cancer it was lower in tamoxifen users (60% and 88%; p < 0.05). The expression of PR in stromal cells was higher in tamoxifen users, both in benign (84% v 54%) and in malignant endometrium (33% v 10%; p < 0.05). Conclusion: The proliferation index (as measured by MIB-1) in benign endometrial epithelium is higher in tamoxifen users than in non-users, and this might play a role in the reported higher incidence of endometrial cancer in postmenopausal tamoxifen users. The increased expression of PR in stroma from tamoxifen users with both benign and malignant endometrium demonstrates an additional oestrogenic effect of tamoxifen on the endometrial stroma.