[Endocrine therapy for advanced or recurrent breast cancer].

Endocrine therapy of advanced or recurrent breast cancer was described. The presence of ER or PgR in primary breast tumors is the best-established marker for response to endocrine therapy. However, ER-positive breast tumors overexpressing EGF-R and/or HER-2 (Erb B2) are resistant to endocrine therapy. Recently it was suggested that an elevated level of the circulating extracellular domain of HER-2 could be a predictor for poor response to endocrine therapy. LH-RH agonist is used as a first-line therapy for premenopausal patients. And LH-RH agonist plus tamoxifen (TAM) has shown a higher response rate and more prolonged survival than LH-RH agonist or TAM alone. As two new aromatase inhibitors, anastrozole (ANA) and letrozole, have shown an equal or higher response rate and a prolonged time to progression than TAM as a first-line therapy, these could be used as a first-line therapy instead of TAM. In a cross-over trial of ANA and TAM, the response rate of ANA after TAM failure was equal to that of TAM after ANA failure. As these drugs showed an equal or higher response rate and longer survival than progestin in TAM resistant cases, these drugs could also used as a second-line therapy. In addition, the trend of recent studies regarding the mechanisms of hormone resistance is also described.