Maturation of vaginal and endometrial epithelium in postmenopausal breast cancer patients receiving long-term tamoxifen.

To assess the estrogenic effects of tamoxifen on vaginal and endometrial epithelium and to investigate whether these changes are associated with any pathological findings in the endometrium, 53 postmenopausal breast cancer patients receiving long-term tamoxifen and 52 control breast cancer patients without any hormonal treatment were examined. Pathological findings in the endometrium were evaluated by hysteroscopy and curettage. The main outcome measures were the maturation index in Papanicolaou (Pap) smears, estrogen-like epithelial changes in the endometrium, serum concentrations of gonadotropins, sex hormone-binding globulin (SHBG), estradiol (E2), and testosterone (T). Informative Pap smears showed estrogenic effects in 89% (41/46) of the tamoxifen group and in 49% (22/45) of the control group, and in endometrial aspiration samples in 71% (32/45) and in 41% (19/46), respectively. These changes were associated with increased concentrations of serum E2 in the control group but not in the tamoxifen group. All five patients (11%) with endometrial polyps in the control group showed estrogenic endometrial changes, whereas among 14 women with polyps in the tamoxifen group, 9 showed estrogenic changes and 5 endometrial atrophy. Endometrial adenocarcinoma was found in 3 patients in the tamoxifen group and in 2 in the control group. Pap smears showed atrophy in 2 patients in the former and in one in the latter group. These findings confirmed estrogen-like effects of tamoxifen on the vaginal and endometrial epithelium in postmenopausal breast cancer patients, but these were not closely associated with benign or malignant endometrial lesions.