[Developments of hormonal agents for breast cancer]

Endocrine therapy for breast cancer, which began with ovariectomy, has a history of more than 100 years. Tamoxifen has been an epoch-making drug during the late 20th century. Recently LHRH analogues which work as downregulators of estrogen production and many aromatase inhibitors (AI), both non-steroidal and steroidal have been developed in Japan. Fadrozole was the only AI until anastrozole was approved a few months ago. Letrozole was shown to be a better AI than fadrozole by prospective randomized double blind examination; however, it is not licenced yet. The reason is that the appropriate dosage is not identical to that of Western countries. We have reached a time when order-made medicine should take into consideration such differences as race and individuality.