A review of endocrine options for the treatment of advanced breast cancer. 
It is now 100 years since it was first recognised that altering the endocrine environment can be valuable in patients with inoperable breast cancer.  Various ablative endocrine and other treatments have since been developed, but few have resulted in a substantial improvement in clinical efficacy, and the response rates to endocrine manoeuvres remain at about 30%.  The benefits of more recent therapies, such as the new generation of aromatase inhibitors, appear to relate to better tolerability and more convenient administration.  It is now recommended that the majority of patients with advanced breast cancer should receive endocrine therapy as their first mode of treatment, although it is postmenopausal patients who are likely to gain most benefit from this approach.  Tamoxifen is currently the first choice of treatment in the majority of postmenopausal women, although most eventually experience progression of disease, possibly because of the partial oestrogen agonist activity of tamoxifen.  Second-line therapy is usually then either an aromatase inhibitor or a progestin.  The new-generation selective, non-steroidal aromatase inhibitors are effective and can offer major clinical benefits in terms of fewer side-effects.