The incidence of bone metastasis from breast cancer is 65% to 75%. The first symptom of distant metastasis from breast cancer is bone metastasis in 27% to 50% of cases. Bone pain, bone injury, bone-related events (SREs) and reduced quality of life are common complications of breast cancer bone metastases. Bone related events include: increased bone pain or new bone pain, pathological fracture (vertebral fracture, non-vertebral fracture), vertebral compression, deformation, spinal cord compression, bone radiotherapy (due to bone pain or prevention of pathological fracture or spinal cord compression), progression of bone metastatic lesions (emergence of new, multiple bone metastases, expansion of existing bone metastases) and hypercalcemia. Diagnostic methods of bone metastasis: 1. Bone radionuclide scan (ECT) is the primary screening diagnostic method for bone metastasis. It has the advantages of high sensitivity, early detection and whole-body imaging, and is not easy to be missed. However, it also has the disadvantages of low specificity, not easy to distinguish osteogenic or osteolytic lesions, and cannot show the degree of bone destruction. Bone ECT is recommended for routine primary screening of breast cancer with bone pain, fracture, elevated alkaline phosphatase, or hypercalcemia, and for further routine staging of breast cancer patients with stage >T3N1M0. Bone ECT is also selectively used for routine staging of breast cancer patients. 2. Magnetic resonance imaging (MRI) scan, or CT scan, or X-ray is the confirmatory imaging test for bone metastasis. For patients with abnormal bone ECT scan, MR, CT, or X-ray should be performed for the suspected bone metastasis site to confirm the diagnosis of bone metastasis and to understand the severity of bone destruction. PET-CT (Positron Emission Computed Tomography) can directly respond to the glucose uptake by tumor cells, and clinical studies have shown that FDG-PET has similar sensitivity and higher specificity than bone scan, and is better than bone scan in the follow-up of breast cancer bone metastases after treatment, However, the expert group believes that the value of PET-CT in the diagnosis of bone metastases needs further study and is not routinely recommended. Therefore, for the clinical diagnosis of bone metastasis, ECT can be used as a primary screening test, X-ray, CT, MRI can clarify the presence of bone destruction, and the value of PET-CT needs to be further studied. For breast cancer patients with confirmed bone metastasis, further routine examinations should be performed: routine blood, creatinine, blood calcium and other liver and kidney functions and blood biochemical indexes; imaging examinations of chest, abdomen and pelvis.