Endocrine treatment of advanced breast cancer.

Endocrine treatment is the preferred first-line therapy for advanced breast cancer because of its good tolerability. There are several groups of agents which differ in their mode of action but almost all in some way reduce stimulation by oestrogen. Over recent years, there has been a substantial increase in the number of medical agents in clinical trial. New antioestrogens with reduced or no agonist activity, and potent, more specific, aromatase inhibitors are now reaching the clinic. In most cases, the clinical effectiveness of these agents remains to be fully established and their optimal therapeutic application is yet to be determined.