Purpose: The estrogenic effects of tamoxifen on the endometrium and the vaginal epithelium are evaluated.
Method: 211 postmenopausal women were examined (tamoxifen group: 176 estrogen-receptor positive breast cancer patients; control group I: 35 estrogen-receptor negative breast cancer patients; control group II: 50 women without breast cancer taking no hormones). We determined the endometrial thickness and the maturation index (MI). Person's chi-square-test and the t-test for independent samples were used.
Results: In the tamoxifen group, the mean endometrial thickness and the MI were significantly higher (p<0.0001) than in the control groups. No evidence of correlation in duration of tamoxifen intake and endometrial thickness was found (Pearson's correlation coefficient: 0.4773; p=0.0001). The maturation index significantly (p<0.0001) increased under tamoxifen therapy. There was no correlation in the maturation index and endometrial thickness (Pearson's correlation coefficient: 0.1649; p=0.169). The histological clarification (N=47; endometrial thickness greater than 8 mm) revealed 3 neoplasms, 9 endometrial polyps, 2 glandular-cystic hyperplasias and in 32 cases atrophic endometrium.
Conclusion: An apparent increase of endometrial thickness and the maturation of the vaginal epithelium caused by the estrogenic effect of tamoxifen was demonstrated.