Effects of toremifene and tamoxifen on lipid profiles in post-menopausal patients with early breast cancer: Interim results from a Japanese Phase III trial

Abstract

Objective: Toremifene and tamoxifen have been used for adjuvant therapy in postmenopausal patients with breast cancer in Japan. Dyslipidemias are common in postmenopausal women. However, limited data are available on the effects of these agents on lipid profiles in Japanese patients. The Japan Toremifene Cooperative Study Group has been conducting a Phase III randomized trial of post-menopausal patients with breast cancer. One of its secondary endpoints is to confirm the effects of these agents on serum lipid profiles. Methods: The subjects were post-menopausal Japanese patients who had undergone surgery for early breast cancer. Toremifene or tamoxifen was administered for 2 years. Lipid levels were measured before and up to 24 months after initiation. Results: Compared with baseline, at 24 months, the toremifene group (n = 123) showed significantly decreased total cholesterol (P < 0.001) and low-density lipoprotein cholesterol levels (P < 0.001), and significantly increased high-density lipoprotein cholesterol levels (P < 0.001). Their triglyceride levels were not affected (P = 0.677). The tamoxifen group (n =120) also showed significantly decreased total cholesterol (P < 0.001) and low-density lipoprotein cholesterol levels (P < 0.001); no significant changes occurred in high-density lipoprotein cholesterol (P = 0.297) or triglyceride levels (P = 0.120). Conclusions: Distinct differences between two selective estrogen receptor modulators on lipids were observed. Toremifene improved lipid profiles, particularly as an enhancer of highdensity lipoprotein cholesterol. To a large extent, tamoxifen improved low-density lipoprotein cholesterol levels. The impact of these improved lipid profiles on the risk of cardiovascular diseases needs further confirmation. © The Author (2010). Published by Oxford University Press. All rights reserved.