Abstract: Endocrine therapy is an important treatment of estrogen receptor (ER) positive breast cancer. However, late relapse after completion of 5year adjuvant endocrine therapy is still common. Extended endocrine therapy (EET) is a promising strategy to further reduce the risk of recurrence and increase the cure rate in earlystage patients. The decisionmaking to EET should be individually implemented by weighing the risk of late recurrence, menopausal status, side effects, and patients′ preference. Future studies are still needed to identify the patients who are most likely to benefit from EET.

Key words:  Breast neoplasms, Prognosis, Tamoxifen, Endocrine therapy