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. 2002 Jul;55(7):514-9.
doi: 10.1136/jcp.55.7.514.

The effects of tamoxifen on proliferation and steroid receptor expression in postmenopausal endometrium

M J E Mourits  1 , K A Ten Hoor, A G J van der Zee, P H B Willemse, E G E de Vries, H Hollema
Affiliations

The effects of tamoxifen on proliferation and steroid receptor expression in postmenopausal endometrium

M J E Mourits et al. J Clin Pathol. 2002 Jul.

Abstract

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.

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Figures

Figure 1
Figure 1
Haematoxylin and eosin staining of endometrial epithelium in a tamoxifen user. Note the flattened monolayered epithelium lining cystically dilated glands and the cell rich stroma, responsible for the irregular ultrasonographic thickening of the endometrium.
Figure 2
Figure 2
MIB-1 staining in the nuclei of the glandular epithelium of benign endometrium in a tamoxifen user.
Figure 3
Figure 3
Oestrogen receptor staining in an endometrioid adenocarcinoma of the endometrium in a tamoxifen user. Note the positive staining in the basal glands and negative staining in the tumour cells.
Figure 4
Figure 4
Progesterone receptor staining in the epithelial and stromal cells of benign endometrium in a tamoxifen user.
See this image and copyright information in PMC

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