Oestrogen receptors, growth factors and the control of breast cancer

The oestrogen receptor (ER) has proved to be a valuable target for the trea tment and prevention of breast cancer. Tamoxifen, a non-steroid antioestrog en. is the endocrine treatment of choice for all stages of ER-positive brea st cancer. However, drug resistance, in the form of tamoxifen-stimulated gr owth, has focused on the new aromatase inhibitors (anastrozole, letrozole) and pure antioestrogens (faslodex) as first-line therapies for advanced bre ast cancer. Tamoxifen is the first selective oestrogen receptor modulator ( SERM). It is antioestrogenic in the breast, but oestrogen-like in bone. Tam oxifen is also the first drug used to prevent breast cancer with the advant age of lowering cholesterol and maintaining bone density. Conversely, ralox ifene, a related SERM, is used to prevent osteoporosis and is being tested as a preventative for breast cancer and coronary heart disease. The discove ry of differences between tamoxifen and raloxifene ER complexes opens the d oor to developing new SERMs. (C) 2001 Harcourt Publishers Ltd.