The effect of the anti-estrogen tamoxifen on cardiovascular risk factors in normal postmenopausal women.

There is growing interest in the use of anti-estrogens as agents of disease prevention. Studies of women with breast cancer suggest that the synthetic anti-estrogen tamoxifen may reduce the incidence of cardiovascular disease, but the effects of this agent on cardiovascular risk factors in healthy women have not been studied. We have performed a two-year, randomized, placebo-controlled trial to assess the effects of tamoxifen 20 mg/day on serum lipids, fibrinogen, and body composition in 57 normal postmenopausal women. Tamoxifen treatment lowered levels of serum cholesterol by (mean +/- SE) 12 +/- 2%, low density lipoprotein cholesterol by 19 +/- 3%, and fibrinogen by 18 +/- 4% (P < 0.0001 vs. placebo for each). Levels of high density lipoprotein cholesterol were not altered by tamoxifen, but the ratio of total cholesterol to HDL-cholesterol decreased by 11 +/- 4% (P < 0.001 vs. placebo). Tamoxifen did not affect levels of triglycerides, high density lipoprotein cholesterol subfractions, apolipoprotein A1, or glucose, and did not change body weight, body mass index, or body fat distribution. We conclude that tamoxifen significantly reduces the levels of atherogenic lipids and fibrinogen in normal postmenopausal women. The results suggest that the anti-estrogens may substantially reduce the risk of cardiovascular disease, which remains the most common cause of death among postmenopausal women.