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 postmenopau sal women with early stage breast cancer. The levels of erythrocyte li pid peroxidation and the status of erythrocyte detoxifying enzymes wer e 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. Th e 3 months and 6 months tamoxifen-treated patients showed significantl y decreased levels of erythrocyte, erythrocyte membrane lipid peroxide with concomitantly increased levels of detoxifying enzymes when compa red with baseline values of untreated women. Erythrocyte membrane chol esterol and phospholipid levels were markedly decreased in tamoxifen-t reated patients than in untreated women. An interesting finding of thi s study indicates that the lipid peroxide, as well as, the lipid lower ing efficacy of tamoxifen, was increased in patients with greater leve ls of baseline lipid and lipid peroxides in their erythrocyte membrane . These results indicate that tamoxifen is a potent suppressor of lipi d peroxide formation through the favorable effects on membrane lipids and protective enzyme system.