Antiatherogenic effects of adjuvant antiestrogens: A randomized trial comparing the effects of tamoxifen and toremifene on plasma lipid levels in postmenopausal women with node-positive breast cancer

Purpose: To evaluate whether a novel antiestrogen, toremifene, has similar antiatherogenic effects as tamoxifen. Patients and Methods: Forty-nine postmenopausal patients with node-positive breast cancer were randomized in a trial that compared the effects of tamoxifen and toremifene on serum lipoproteins. Tamoxifen was given at 20 mg and toremifene at 60 mg orally per day for 3 years. Serum concentrations of apolipoprotein (apo) A-I, A-II, and B, and lipoprotein(a) [Lp(a)], cholesterol, triglyceride, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, follicle-stimulating hormone (FSH), luteinizing hormone (LH), and estradiol were measured before and after 12 months of antiestrogen therapy. Results: Both antiestrogens significantly reduced serum and LDL cholesterol and apo B levels. However, the response of HDL cholesterol to treatments was clearly different between the groups. Toremifene increased the HDL level by 14%, whereas tamoxifen decreased it by 5% (P=.001). As a consequence, both cholesterol-to-HDL and LDL-to-HDL ratios decreased more in the toremifene than tamoxifen group (P=.008 and P=.03, respectively). Toremifene also increased the apo A-I level (P =.00007) and apo A-I-to-A-II ratio (P=.018). Both tamoxifen and toremifene decreased the Lp(a) concentration significantly (change, 34% v 41%). Conclusion: These results provide positive evidence that toremifene has antiatherogenic properties with potency to improve all lipoproteins that are associated with increased coronary heart disease (CHD) risk. (C) 1996 by American Society of Clinical Oncology.