Inclusion Criteria:  Age≥18 years old; Both or either ER+ or PgR+, and human epidermal growth factor receptor type 2 (HER-2)-negative primary tumor; T1-T3, any N, and M0 according to the TNM classification; Any type of breast surgery (includes breast conserving surgery and breast cancer radical surgery); Any type of preoperative and/or postoperative adjuvant chemotherapy prior to enrollment; History of regular menstruation and not having chemical menopause (FSH≥40 mIU/mL and E2<10 pg/mL) within 12 weeks after completion of the postoperative chemotherapy; Previously using GnRH-a 1M or 3M as OFS treatment for at least one time; Capable of receiving other study drug like Tamoxifen or AI; Eastern Cooperative Oncology Group performance status of Grade 0 or 1.  Exclusion Criteria:  Uncapable of receiving endocrine therapy for any clinical or other reason; Bilateral oophorectomy or ovarian irradiation Inflammatory breast cancer or bilateral breast cancer; Multiple cancers or a history of cancer in other organs; Patients with other non-malignant systemic diseases (cardiovascular, renal, hepatic, lung, etc.) that would prevent prolonged follow-up.