Serum lipid levels during and after adjuvant toremifene or tamoxifen therapy for breast cancer

Tamoxifen decreases serum cholesterol (S-cholesterol) level about 10% and l ow-density lipoprotein cholesterol (S-LDL) 15-20%, but in most studies it h as increased serum triglyceride levels and had little effect on serum high- density cholesterol (S-HDL). The effect of another antiestrogen, toremifene , on the serum lipid profile has not been completely studied. We monitored serum lipid levels longitudinally in 141 axillary node-positive postmenopau sal breast cancer patients who received randomly either 40 mg toremifene or 20 mg tamoxifen as adjuvant therapy for 36 months, and in 34 postmenopausa l women who received no adjuvant systemic therapy after surgery for axillar y node-negative breast cancer. No significant differences were found betwee n the drugs in their effects on S-cholesterol, LDL, HDL, or triglyceride le vels, or on the cholesterol-to-HDL or LDL-to-HDL ratios. For both drugs the S-cholesterol and S-LDL absolute lowering effect was the greater the highe r the pretreatment level. For a patient with a median pretreatment value, t oremifene decreased S-cholesterol 6% and tamoxifen 13%, and S-LDL decreased by 13% and 23%, respectively, at 6 months of therapy. Six months after sto pping three-year antiestrogen therapy S- cholesterol and S-LDL levels had r eturned to the pretreatment levels. In conclusion, we found no major differ ences between 40 mg toremifene and 20 mg of tamoxifen in their effect on th e serum lipid levels, which return to the pretreatment levels within 6 mont hs after cessation of therapy.