Effects of tamoxifen on serum lipid and apolipoprotein levels in postmenopausal patients with breast cancer.

Serum lipids and apolipoprotein levels were measured in twenty postmenopausal women with primary breast cancer, before and three months after tamoxifen therapy (10 mg twice a day). Tamoxifen caused a significant reduction in total serum cholesterol (10%; P < 0.02), and in low-density lipoprotein cholesterol (17%; P < 0.01), and a significant 47% increase in the subclass 2 of the high density lipoprotein cholesterol (P < 0.01). In addition, tamoxifen caused a 16% increase in apolipoprotein A-I, a 12% decrease in apolipoprotein B (P < 0.05), and a 37% reduction in the serum concentration of lipoprotein (a) (P < 0.01). These results show that tamoxifen brings about an important improvement in serum lipid profile.