Recent Progress and Future Perspective of Endocrine Therapy for Breast Cancer

ABSTRACT Endocrine therapy is the classical target therapy applying to major part of breast cancer patients. At present, there are sub-classes of drug called aromatase inhinitor (AI), selective estrogen receptor modulator (SERM), selective estrogen receptor down-regulator (SERD), progestin and estrogen derivatives. Although novel predictive factor for endocrine therapy has never been added to date other than the presence of ER and/or PgR, recent progress gave us some insight of such factors related to patient herself. CYP2D6 genotype for tamoxifen metabolism and body mass index for AI response are those arising from individual patient difference, but related to the response of drug in some degree. In addition, combination with other molecular pathway drugs such as anti-HER2 agents, mTOR inhibitor and anti-angiogenesis drug have been intensively investigated, showing double, triple or more simultaneous pathway blocking approach may have dramatic response to hormone receptor (HR) + breast cancer. From the point of view that these HR + tumors generally showed poor response to conventional chemotherapy, these approaches seem to be leading edge for improvement of this subtype of cancer patients.