[Tamoxifen-induced severe hypertriglyceridemia--report of 3 cases].

Tamoxifen, an anti-estrogen, has been used for a long time as an adjuvant therapy in cases of estrogen receptor positive breast cancer. Tamoxifen also demonstrates some weak estrogenic activity. A small increase in serum triglycerides is commonly found after tamoxifen administration. Herein we report 3 cases of sever hypertriglyceridemia due to tamoxifen. Case 1 recovered with tamoxifen withdrawal. Tamoxifen was replaced with toremifene in case 2. The level of triglyceride decreased significantly after the change of agent. Tamoxifen was discontinued and anastrozole administration was started in the third patient. Her triglyceride levels improved. Tamoxifen-induced severe hypertriglyceridemia seen in these patients was an effect of its estrogen action. Anastrozole has been used to treat postmenopausal metastatic breast cancer, and several clinical trials in the adjuvant setting are ongoing. Anastrozole does not affect lipid metabolism. Therefore, anstrozole might be safe for patiens with abnormal triglyceride profiles during tamoxifen treatment. We recommended that a periodic serum triglyceride check is needed for patients treated with tamoxifen.