Intracranial metastasis refers to the metastasis of malignant tumors from other parts of the body into the skull. Generally speaking, the incidence of intracranial metastasis is 25%-30%, and among various cancers, lung cancer, gastrointestinal tract cancer and breast cancer have the highest number of deaths and intracranial metastases. 1.Treatment principle Adopt comprehensive treatment and emphasize general treatment: comprehensive treatment is better than single treatment, which helps to improve the efficacy and prolong life. Emphasis on general treatment provides conditions for comprehensive treatment such as surgery and radiotherapy. Determine whether to treat brain metastases or the primary tumor first according to the disease duration and condition. Select treatment plans according to the specific conditions of patients with brain metastases. Regularly follow up the organs of the primary cancer and other organs, observe the treatment of the primary cancer and metastases, and monitor new metastases. If new brain metastases appear, further appropriate treatment plan should be selected according to the specific situation. 2.Common treatment measures: including steroid hormone, surgery, radiotherapy, stereotactic radiosurgery, intra-tumor therapy and chemotherapy, etc. With the progress of neurosurgery, radiation diagnosis technology and treatment, the efficacy and prognosis of intracranial metastases have improved, and the 1-year survival rate after surgery has been improved, and the 1-year survival rate is even higher if radiotherapy and/or chemotherapy are added after surgery. The ideal treatment should be chosen according to each patient’s specific situation. Currently, the idea of surgery combined with postoperative radiotherapy is well accepted, and the combination has shown promising results, but it should be noted that these treatments are only palliative, and only 8-10% of those for whom the primary tumor cannot be found can be cured. Craniotomy for metastases: In recent years, it is the consensus of all clinical workers to actively and effectively resect intracranial metastases, and how to choose the indication is related to the patient’s prognosis. (1) Patients with good general condition, no contraindications to other vital organs, and who can tolerate general anesthesia. (2) The lesion is single, located at a resectable site, and the patient is not expected to have significant postoperative complications such as hemiparesis, aphasia, or coma. (3) The primary lesion has been resected without recurrence, or the primary lesion has not been resected but can be resected, and the symptoms of increased intracranial pressure are obvious and need to be removed by craniotomy first to reduce the symptoms of increased intracranial pressure. (4) For those who have stroke or cystic change of tumor leading to limb paralysis or even coma, craniotomy should be performed to save patients’ lives as much as possible. (5) A single isolated lesion that cannot be clearly diagnosed should be surgically removed to determine whether it is a metastatic tumor. Aggressive craniotomy to remove intracranial metastases can prolong the patient’s life, and conditions should be created to maximize the treatment. If the patient cannot tolerate surgery due to poor general condition or multiple lesions cannot be surgically removed with one incision, palliative surgery can be performed. The former is to maximize the relief of increased intracranial pressure, but the effect is not ideal; the latter is suitable for patients with cystic metastases, and the cystic fluid can be released by puncturing the cystic cavity with a rapid fine hole drilling method, which is easy to perform and can also create conditions for X- or γ-knife treatment. Patients with metastases often have a short course of disease and obvious cerebral edema, which makes the symptoms of increased intracranial pressure appear earlier and more obvious. In recent years, due to the application and development of X-knife and γ-knife, the treatment means of intracranial metastases have been further broadened. The indications are: (1) The patient is in poor general condition and cannot tolerate craniotomy. (2) The metastases are located in important functional areas, and surgery may cause serious complications and affect the quality of survival. (3) Multiple metastases cannot be removed in one operation, or metastases in other areas appear after craniotomy, or patients are unwilling to undergo surgery, or the main metastases are removed by craniotomy, and adjuvant treatment is performed for tumors that cannot be easily removed at the same time. Due to the limitations of X- and γ-knife itself, it is better to select substantial tumors with diameters below 3-4 cm, and those with cystic lesions can be treated after aspiration of cystic fluid by puncture first. Radiation therapy is a very important supplement for postoperative patients and can be performed for inoperable patients. Because intracranial metastases are most common in bloodstream metastases, the tumor emboli can be widely present in the cerebral vessels or in the brain, and radiation can further kill these emboli. 60Co or 8MV X-rays are commonly used for treatment. During radiotherapy, dehydrating drugs and hormone therapy can be applied to reduce the response to radiotherapy. It is generally believed that the dose of single radiotherapy must be higher than 40Gy to be effective. Chemotherapy can be administered regardless of whether the patient has undergone surgery or not, if the patient’s general condition is good and the blood routine, liver and kidney function are normal. Generally, sensitive chemotherapy drugs are selected according to the nature of the primary tumor. On the other hand, chemotherapy can kill subclinical lesions in extracranial primary organs, control the development of visible tumor foci, and work synergistically with radiotherapy to improve the prognosis.