The effects of tamoxifen on the endometrium, blood flow of the uterine arteries and serum lipoprotein (a) levels in postmenopausal women

Abstract

The purpose of this study was to evaluate the effect of tamoxifen therapy on the endometrium by transvaginal color Doppler sonography and on lipid profile focusing on lipoprotein (a) [Lp(a)] levels. Seventy-five postmenopausal breast cancer patients were examined by transvaginal color Doppler sonography and serum Lp(a) levels. Lipid parameters were measured after overnight fasting. Forty of the patients were treated with tamoxifen (20-30 mg/day) for at least 1 year. The remaining 35 patients did not receive tamoxifen and were used as controls. Statistical analysis was performed using t-test and Mann-Whitney U-test (Systat version 5.0). The patients receiving tamoxifen had significantly thicker endometrium (7.9 ± 3.6 mm) compared to the control group (4.5 ± 1.8 mm) (p ≤ 0.001). The mean pulsatility index and resistance index of the uterine arteries in the tamoxifen group were 2.063 ± 0.49 and 0.83 ± 0.07, respectively, and were significantly lower than those of the control group (2.69 ± 0.16 and 0.88 ± 0.02) (p < 0.001). In addition, tamoxifen decreased total cholesterol (p < 0.001) and low-density lipoprotein cholesterol (p < 0.001) and apolipoprotein B (p < 0.05) significantly. Tamoxifen also increased high-density lipoprotein cholesterol (p < 0.05) and apolipoprotein A-I (p < 0.05). These results indicate that tamoxifen stimulates the endometrium and acts as an anti-atherogenic agent in postmenopausal women.