Differential effects of selective estrogen receptor modulators and estrogens on mammary blood flow in the ovine

Different forms of estrogen and drugs that block estrogen have different effects on blood flow in the breast, according to a study in sheep. Estradiol-17beta, conjugated equine estrogen, and tibolone increased blood flow in the breast, whereas tamoxifen and raloxifene did not. Breast cancer is characterized by increased blood flow in the breast.