Malignant tumors can develop bone metastases, and breast and prostate cancers account for about 80% of patients with bone metastases. Tumor cells destroy bone and cause severe bone pain, and pathological fractures and hypercalcemia can occur. Bisphosphonates are one of the drugs currently used to treat bone metastases from malignant tumors. Nitrogen-containing bisphosphonates (zoledronic acid) have a powerful inhibitory effect on bone resorption and can affect osteoclast function by inhibiting protein isoprenylation, leading to apoptosis. At present, a variety of imported and domestic zoledronic acid are commonly used in clinical practice. I. Mechanism of action of zoledronic acid includes: 1. inhibition of osteoclast maturation 2. inhibition of osteoclast aggregation at the site of bone resorption 3. inhibition of mature osteoclast function 4. reduction of cytokine production (such as interleukin [IL]-6) 5. direct anti-tumor activity (cell proliferation inhibition and cytolysis) 6. inhibition of tumor cell proliferation, infiltration and adhesion to the bone matrix 7. anti-angiogenic effect II. Adverse reactions: Adverse reactions of zoledronic acid occur in about 1/3 of patients. The most frequent are flu-like symptoms (about 9%), including bone pain (9.1%), fever (7.2%), fatigue (4.1%), chills (2.8%), and arthralgia and myalgia (about 3%), renal impairment (2.3%), and osteonecrosis of the jaw. Dosage: For breast cancer patients with bone metastases, zoledronic acid 4mg, diluted with 0.9% NaCl or 5% glucose solution 100ml, intravenous infusion, once a month. For breast cancer patients, although no bone metastasis occurs during endocrine therapy, in order to prevent bone metastasis, increase bone density and reduce tumor recurrence rate, zoledronic acid 4mg, diluted with 0.9% NaCl or 5% glucose solution 100ml, should be infused intravenously once every 6 months. 4. Precautions: Also drink more water and rehydration Check electrolytes and renal function, such as serum calcium, phosphorus, magnesium and creatinine level. Monitor renal function closely.