Treatment with fulvestrant is required until disease progression occurs or fulvestrant resistance or adverse reactions develop. Fulvestrant is an estrogen receptor antagonist used for locally advanced or metastatic postmenopausal (both naturally and artificially menopausal) estrogen receptor-positive breast cancer that has recurred after or during adjuvant anti-estrogen therapy or that has progressed on anti-estrogen therapy. The recommended dose for adult women is 250 mg administered once a month. The most common adverse reactions during the use of this drug are nausea and vomiting, constipation, abdominal pain, diarrhea, headache, and back pain. Mild transient pain and inflammation, blood clots, and myalgia are seen at the injection site. Vaginal bleeding can also occur in a few patients. For this drug is contraindicated in pregnant women, premenopausal women and children. Anti-tumor drugs need to clarify the type and specific progress of the patient’s tumor before use, and follow the doctor’s instructions to choose the appropriate dose for treatment.