Menopause is generally defined as the permanent termination of menstruation and is also used to describe the permanent loss of estrogenic function synthesized by the ovaries during breast cancer treatment. The definition of menopause can be referred to the following criteria: 1. post bilateral oophorectomy 2. age ≥ 60 years 3. age < 60 years and menopause without chemotherapy and treatment with tamoxifen, toremifene and ovarian function inhibitors for ≥ 12 months, while blood FSH and estradiol levels are within the postmenopausal range. In contrast, patients with menopause who are taking tamoxifen and toremifene and are <60 years of age, serial testing of blood FSH and estradiol levels in the postmenopausal range is required. It is also important to note that: 1. Women who are receiving LH-RH agonists or antagonists cannot be determined to be menopausal. 2. In women who were not menopausal before adjuvant chemotherapy, menopause cannot be used as a basis for determining menopause because although the patient may stop ovulating or have no menstruation after chemotherapy, ovarian function may still be normal or may be restored. 3. For women with chemotherapy-induced menopause, if aromatase inhibitors are considered as endocrine therapy, effective ovarian suppression (complete bilateral ovariectomy or pharmacological suppression) or serial testing of FSH and/or estradiol levels to confirm that the patient is in a postmenopausal state is required.