Effect of tamoxifen on erythrocyte membrane lipids, lipid peroxides, and antioxidative enzymes in breast cancer women.

Fasting blood samples were taken from 64 tamoxifen-treated postmenopausal women with early stage breast cancer. The levels of erythrocyte lipid peroxidation and the status of erythrocyte detoxifying enzymes were analyzed in untreated and treated patients for 3 months and 6 months with tamoxifen. Erythrocyte membrane lipid peroxidation and membrane cholesterol, phospholipid were also determined in all the patients. The 3 months and 6 months tamoxifen-treated patients showed significantly decreased levels of erythrocyte, erythrocyte membrane lipid peroxide with concomitantly increased levels of detoxifying enzymes when compared with baseline values of untreated women. Erythrocyte membrane cholesterol and phospholipid levels were markedly decreased in tamoxifen-treated patients than in untreated women. An interesting finding of this study indicates that the lipid peroxide, as well as, the lipid lowering efficacy of tamoxifen, was increased in patients with greater levels of baseline lipid and lipid peroxides in their erythrocyte membrane. These results indicate that tamoxifen is a potent suppressor of lipid peroxide formation through the favorable effects on membrane lipids and protective enzyme system.