65 The effects of tamoxifen and toremifene on plasma lipid levels in postmenopausal early breast cancer patients

Abstract

Tamoxifen as adjuvant therapy for women with breast cancer decreases serum lipids and lipoproteins by its estrogenic agonist effects. We evaluated whether a novel antiestrogen, toremifene, has similar effects. Patients and Methods 49 postmenopausal early breast cancer patients were randomized to adjuvant tamoxifen or toremifene treatment groups. Total, LDL and HDL cholesterol, apolipoprotein A-I, A-II and B and Lp(a) were measured before treatment and after 12 months. Results Both antiestrogens reduced significantly serum total and LDL cholesterol and apo B levels. The response of HDL cholesterol to treatment was clearly different between the groups. Toremifene increased the HDL-Ievel 14% whereas tamoxifen decreased it 5% ( P = 0.001). Both Chol/HDL and LDL/HDL ratios fell more in the toremifene than tamoxifen group (P = 0.008; p = 0.03, respectively). Toremifene also increased apo A-I level ( P = 0.00007) and apo A-I/A-II ratio ( P = 0.018). In both tamoxifen and toremifene treatment groups Lp(a) concentration fell significantly (change: 34% vs 41%). Conclusion These results provide positive evidence that toremifene has highly antiatherogenic properties with an exceptional potency to improve all lipoproteins which are associated with increased coronary heart disease risk.