Recurrence of breast cancer is the leading cause of death in breast cancer patients. According to relevant data, the 5-year survival rate of bone metastasis due to breast cancer recurrence is only 16%, the 5-year survival rate of lung metastasis is only 12%, and the 5-year survival rate of liver metastasis is even zero. Therefore, postoperative prevention of recurrence is especially critical for breast cancer patients. Many patients have a misconception that the treatment of breast cancer is purely surgical, and as long as the cut is clean, there will be no recurrence. The medical community has now reached a consensus that breast cancer is a systemic disease, not just a localized tumor. Therefore, the treatment of breast cancer must be standardized, combining surgery with radiotherapy, chemotherapy and endocrine therapy; surgery alone cannot completely solve the problem. Compared to other tumors, the most important feature of breast cancer is that its occurrence and progression are related to estrogen levels in the body and its metabolism. For positive estrogen and progesterone receptors, especially for positive patients with high response, endocrine therapy is the most effective means to reduce the risk of recurrence. The principle is to inhibit or reduce the secretion of estrogen and lower its level or block the pathway of estrogen action, thus blocking the source of “nutrients” on which the tumor lives. Since 5 years after surgery is the peak period for breast cancer recurrence, endocrine therapy should be adhered to for 5 years, and some patients need to adhere to it for a longer period. Currently, the main endocrine therapy drugs are estrogen receptor antagonists such as triamcinolone acetonide and aromatase inhibitors, of which triamcinolone acetonide has been used for more than 40 years and is an endocrine therapy drug for all ages. The principle is to block estrogen so that it cannot bind to the receptor, while the principle of aromatase inhibitors is to reduce and inhibit estrogen production in postmenopausal women. In contrast, for postmenopausal patients with hormone receptor-positive early-stage breast cancer, the principle of aromatase inhibitors is more scientific and more effective. Currently, aromatase inhibitors have become the standard regimen of adjuvant endocrine therapy for postmenopausal estrogen and/or progesterone receptor positive breast cancer, further reducing the risk of recurrence by 24%, the risk of distant metastases by 16%, and the risk of contralateral breast cancer by 40% on top of triamcinolone. Patients with breast cancer should not be deterred from treatment by fear of side effects of subsequent treatment, as the benefits to patients far outweigh the side effects.