The side effects of endocrine therapy for breast cancer are mainly related to the endocrine drugs taken. Because the endocrine treatment for breast cancer is mainly for estrogen and progesterone receptor positive patients, according to whether the patients are menopausal or not, the endocrine treatment is carried out with aromatase inhibitors (such as letrozole, anastrozole or exemestane tablets) or tamoxifen respectively, which can effectively reduce the risk of recurrence and metastasis of breast cancer, and the course of the treatment is usually 5 years, and there is a possibility of endometrial carcinoma occurring when taking tamoxifen. Therefore, for patients taking tamoxifen for breast cancer treatment, regular gynecological examination is needed to prevent the occurrence of endometrial cancer. The main side effect of taking aromatase inhibitors is osteoporosis, so it is necessary to take calcium tablets and vitamin D3 together with it. For the current treatment of breast cancer, the first choice or prerequisite is surgical excision, followed by axillary lymph node dissection, with postoperative chemotherapy, radiotherapy, endocrine therapy, and even molecular targeting drug therapy, and the purpose of subsequent treatment is to remove the residual cancer cells above and reduce the risk of recurrence or metastasis, so as to comprehensively improve the overall management of breast cancer, and to increase the risk of metastasis. The purpose of follow-up treatment is to remove the remaining cancer cells and reduce the risk of breast recurrence or metastasis, so as to comprehensively improve the cure rate of breast cancer.