Statement: Cohort 2 of the primary trial is the control group, as the Eligible patients with breast cancer treated with GnRHa every 28 days.
Primary_evidence: INTERVENTION 1:    GnRHa (Gonadotrophin-releasing Hormone Analogues) Group   Eligible patients with breast cancer treated with GnRHa (Gonadotrophin-releasing Hormone Analogues) while receiving chemotherapy.   Goserelin 3.6mg, or leuprorelin 3.75mg subcutaneous injection every 28 days.Initiated 1-2 weeks before chemotherapy and ended 4-8 weeks after chemotherapy. INTERVENTION 2:    None GnRHa (Gonadotrophin-releasing Hormone Analogues) Group   Eligible patients with breast cancer treated without GnRHa (Gonadotrophin-releasing Hormone Analogues) while receiving chemotherapy.