Menopause is a normal female physiological phenomenon, but the definition of menopause varies greatly in different professional books, from 1 to 2 years or even 5 years after cessation of menstruation, leaving clinicians and patients at a loss as the indications for some drugs are only applicable to postmenopausal women, such as Letrozole and Renintex in endocrine therapy for breast cancer. Menopause generally refers to the permanent termination of menstruation and is also used to describe the persistent reduction of estrogen synthesized by the ovaries during the course of breast cancer treatment. There are several clear definitions of menopause: 1. post bilateral oophorectomy; 2. age” 60 years; 3. age < 60 years, menopause" 12 months, not receiving chemotherapy, tamoxifen, toremifene or ovarian function suppression therapy, and FSH and estradiol levels are within the postmenopausal range; 4. age < 60 years, taking tamoxifen or toremifene, FSH and estradiol levels should be within the postmenopausal range; 5. age < 60 years, taking tamoxifen or toremifene, FSH and estradiol levels should be within the 5. Patients receiving LH-RH agonists or antagonists cannot be determined to be menopausal; 6. In premenopausal women receiving adjuvant chemotherapy, menopause cannot be used as a basis for determining menopause; 7. In women with chemotherapy-induced menopause, if an aromatase inhibitor is considered as endocrine therapy, ovariectomy or serial testing of FSH and/or estradiol levels is required to ensure that the patient is in a postmenopausal state.