[Guidelines for clinical diagnosis and treatment of advanced breast cancer in China (2020 Edition)].

Breast cancer is the most common malignant tumor among women all over the world. In 2015, there were about 304, 000 new cases of breast cancer in Chinese female, with more than 70, 000 deaths. Of the new cases of breast cancer each year, about 3% to 10% of patients have distant metastasis at the time of diagnosis. Of the early-stage patients, about 30% developed into advanced breast cancer. The 5-years survival rate of advanced breast cancer was only 20%, and the median overall survival time was 2-3 years. Although advanced breast cancer is difficult to cure at present, we can alleviate the clinical symptoms of patients, improve their quality of life and further prolong their survival time by developing new therapeutic drugs and optimizing treatment models, to achieve the purpose of long-term survival with tumor. It is very important for patients with advanced breast cancer to choose the reasonable treatment plan. Since there is lack of standard recommendation for the treatment of advanced breast cancer after the first and second line chemotherapy, according to the research progress of breast cancer at home and abroad and the update of real-world clinical research data, the Chinese expert group analyzed, summarized and discussed the relevant research data, updated the diagnosis, treatment and prognosis of inoperable locally advanced and recurrent or metastatic breast cancer on the basis of version 2018, and formulated the "Guidelines for clinical diagnosis and treatment of advanced breast cancer in China (2020 Edition)" (ABCC 2020) for clinicians' reference.