Endocrine therapy targeting estrogen pathway is one of the first-line treatment choices of advanced breast cancer. Fulvestrant is a pure estrogen antagonist that blocks and downgrades estrogen receptor, which makes it effective in the treatment of progression after prior endocrine therapy. Fulvestrant 250 mg per month regime was approved for postmenopausal women with hormone-positive advanced breast cancer after progression or recurrence on antiestrogen therapy. Fulvestrant 500 mg per month regime was appro...