Most breast cancer patients need adjuvant endocrine therapy after surgical treatment. Before deciding to use endocrine therapy regimen, it is necessary to determine whether the patient is menopausal or not. Patients who meet the criteria of menopause will get good results with aromatase inhibitors (AIs, such as exemestane, letrozole, etc.). So, how to determine whether a patient is menopausal or not? Currently, the accepted criteria for patients to be menopausal are: 1. post bilateral oophorectomy or post radiation therapy ovarian debulking; 2. patient age greater than or equal to 60 years; 3. patient age less than 60 years with continuous monitoring of blood FSH (follicle stimulating hormone) and E2 (estradiol) levels in the postmenopausal range. It should be emphasized that in women who are not menopausal before adjuvant chemotherapy, menopause cannot be used as a basis for menopause, because although patients will stop ovulation or have no menstruation after chemotherapy, ovarian function may still be normal or have the possibility of recovery; for women with chemotherapy-induced menopause, if AIs are considered as endocrine therapy, effective ovarian suppression (complete bilateral ovariectomy or pharmacological suppression, pharmacological suppression such as monthly outpatient use of Norelide, etc.), or multiple testing of FSH and/or estradiol levels to confirm that the patient is in menopausal status. There is no consensus on the evaluation criteria for hormone level testing. Considering that menopause affects the therapeutic effect of using AIs, Beijing Friendship Hospital of Capital Medical University adopts the most stringent evaluation criteria, i.e. “two highs and one low”, requiring E2 <20 pg/mL; LH >30 IU/L; FSH >40 IU/L. FSH > 40 IU/L, and patients younger than 60 years old who have been tested several times to reach this standard are judged as menopausal patients.