Treatment of advanced breast cancer The main purpose of choosing chemotherapy for advanced breast cancer is to reduce patients’ symptoms, control disease progression and improve survival. In the selection of chemotherapy regimen, attention should also be paid to the toxic side effects caused by chemotherapy to minimize the toxicity of treatment. Depending on the subtype, the median survival after distant metastasis of breast cancer varies, generally ranging from six months to 2.2 years. The overall survival of breast cancer patients has improved significantly over the past 30 years, especially for HER2-positive breast cancers. Metastatic breast cancer is still incurable, but treatment can be used to improve patient survival and quality of life. Hormone therapy For estrogen receptor-positive metastatic breast cancer, hormone therapy remains the first choice. The choice of hormonal treatment regimen should be based on the patient’s previous response to treatment and whether or not she is menopausal. Drug resistance is common and unavoidable in hormonal treatment of metastatic breast cancer. How to avoid the problem of drug resistance is a hot topic of current research. mTOR-mediated signaling pathway is highly activated in breast cancer with high frequency, leading to resistance to hormone therapy and becoming an important target for breast cancer treatment. The results of a study showed that the combination of the mTOR inhibitor everolimus with exemestane in patients with advanced breast cancer prolonged the disease-free progression period and significantly reduced the risk of cancer progression by 57% compared to exemestane alone. Everolimus can produce serious side effects, including: stomatitis, rash, diarrhea and malaise, and pneumonia is also common. These side effects should be noted during the course of treatment and treated early if they occur. Everolimus has been approved in North America and Europe for the treatment of patients with hormone receptor-positive, HER2-positive breast cancer. Chemotherapy Chemotherapy is commonly used for the following types of breast cancer: hormone therapy-resistant breast cancer, hormone receptor-negative breast cancer, rapidly progressive breast cancer, and most HER2-positive breast cancers. The choice of chemotherapy regimen should be tailored to the patient’s physical condition and the nature of the tumor (e.g., triple-negative breast cancer, HER2-positive) as well as previous response to chemotherapy. Chemotherapy is usually a short course of treatment, completed for a few cycles. There is no uniform conclusion as to the exact number of courses of chemotherapy needed. HER2-targeted therapy Before targeted drugs came out, HER2-positive breast cancer patients were considered to be the category with poor prognosis. With the advent of humanized monoclonal antibodies targeting HER2, the prognosis of this group of patients has improved significantly. Trastuzumab in combination with paclitaxel significantly improved patient survival in neoadjuvant therapy for HER2-positive breast cancer. Patients with HER2-positive breast cancer who have failed trastuzumab therapy may choose lapatinib, a small molecule kinase inhibitor. Lapatinib is currently approved for second-line use in combination with capecitabine for the treatment of HER2-positive breast cancer. Trastuzumab emtansine (T-DM1) is an antibody-drug coupled drug for the treatment of HER2-positive breast cancer. the EMILIA study showed that the experimental new drug T-DM1 was better tolerated compared to the capecitabine/lapatinib (XL) combination in 978 patients with HER2-positive metastatic breast cancer, and significantly prolonged progression-free survival and overall survival. As a result of these new agents, the median survival of HER2-positive metastatic breast cancer patients has significantly improved over the past 3 years.