Tamoxifen use and endometrial lesions: hysteroscopic, histological, and immunohistochemical findings in postmenopausal women with breast cancer.

OBJECTIVE

To evaluate immunohistochemical, hysteroscopic, and histological findings in postmenopausal women taking tamoxifen for breast cancer.

METHODS

Forty postmenopausal women taking 20 mg/day tamoxifen for breast cancer underwent hysteroscopy and endometrial biopsy from January 2000 to December 2003. Medical records and paraffin blocks were analyzed retrospectively, and Ki-67, estrogen receptors (ERs), and progesterone receptors were measured using an immunohistochemical technique.

RESULTS

The mean +/- SD age of the women was 59 +/- 14 years at hysteroscopy (95% CI, 54.2-63.7) and 45.1 +/- 7 years at menopause (95% CI, 42.6-47.6). Mean +/- SD duration of tamoxifen therapy was 27.3 +/- 16.5 months (95% CI, 22.0-32.5). Hysteroscopies were performed because of abnormal sonographic findings in 60% of the women and postmenopausal bleeding in 40%. The most common hysteroscopic and histological findings were endometrial polyps (32.5%) and atrophic endometria (22.5%). Immunohistochemistry showed that 85% of the women were progesterone receptor positive, 75% were ER positive, and 50% were Ki-67 positive. Endometrial polyps and polyps associated with atrophic endometrium were ER positive (P = 0.019). Results that were ER negative were more frequent in atrophic endometria (P = 0.01). The longer the time since menopause, the lower the Ki-67 expression in the endometrium was (P = 0.03). Ki-67 expression was greater in the endometrium of younger postmenopausal women (P = 0.01).

CONCLUSIONS

The expression of steroid receptors in the endometrium was high in our series. All cases of endometrial polyps were ER positive. Estrogen receptors may play a major role in the development of endometrial polyps in postmenopausal women taking tamoxifen. Although most histological findings were benign, 22.5% were atrophic.