Endocrine therapy is preferred for patients with recurrent metastatic breast cancer who meet all of the following criteria: first, hormone receptor positivity; second, relatively slow disease progression; third, long disease-free survival after breast cancer surgery (metastasis occurs after more than two years of adjuvant endocrine therapy); and fourth, a relatively light tumor load with no symptoms that require rapid relief. Overall, it means that endocrine therapy is preferred for patients with relatively mild disease. In addition to endocrine therapy for recurrent metastatic breast cancer patients with the above conditions, endocrine therapy is also used for postoperative adjuvant therapy for hormone receptor-positive early-stage breast cancer (i.e., prevention of recurrence and metastasis), and progestins are also used to enhance the appetite and improve the physical state of patients who have poor appetite after chemotherapy or due to the condition of the disease.