[Introduction of new drug: letrozole, a new non-steroidal aromatase inhibitor for the treatment of postmenopausal women with breast cancer].

Recently, a new non-steroidal aromatase inhibitor, letrozole (Femara tablet 2.5 mg) launched in Japan for the treatment of postmenopausal women with breast cancer. This drug has triazole structure, as similar drug, anastrozole (Arimidex). Currently, this drug has been put on markets in more than 80 countries, in which more than 20 countries have approved the use for the extended adjuvant treatment of early breast cancer. Letrozole is an oral drug given once daily and the first choice for the treatment of patients with steroid receptor positive or receptor-unknown locally advanced or metastatic postmenopausal breast cancer. As for the adverse events, they are mostly mild, including hot flashes, arthritis, miyalgia, and such as nausea, fatigue, anorexia, hyperorexia, edema, headache, vertigo, vomition and others. In the large international breast cancer studies, beneficial results were obtained for the post-surgical endocrine therapy of postmenopausal women with breast cancer, and the similar use of this drug has been approved in Japan.