Brain metastases are the most common malignant lesions in the skull, occurring more frequently than primary malignant brain tumors, and are caused by malignant tumor cells from other parts of the body that metastasize through the blood system and grow in the skull. According to statistics, about 20%-40% of patients with malignant tumors develop brain metastases. The incidence of brain metastasis has a trend of increasing year by year, which may be related to the increasing life expectancy of cancer patients and the popularity of imaging devices such as CT and MRI. First, a comprehensive assessment of intracranial lesions The clinical presentation of patients with brain metastases is not specific, especially for single intracranial lesions, and is often misdiagnosed. In patients older than 50 years with intracranial occupancy, the possibility of metastases should be considered. The sensitivity and anatomical resolution of cranial MRI plain plus enhanced is significantly better than CT. brain metastases are mostly located in the subcortex, 70% are multiple and 30% are solitary. Some metastases, such as colon cancer, osteosarcoma and melanoma, may show low signal on T2WI. The cystic portion of brain metastases shows low signal on T1WI and high signal on T2WI. Under Gd-DTPA enhancement, substantial metastases show homogeneous enhancement, while those with cystic lesions show ring-like enhancement. To the extent possible, the site of the primary tumor should be determined. The determination of the primary site is of key importance in the management of brain metastases. For patients with intracranial occupancy and suspected brain metastasis, meticulous physical examination, serum tumor marker examination and imaging examination should be performed. In terms of physical examination, abnormal masses, superficial lymph nodes, skin nevi, female breast and male prostate should be examined. Although serum tumor markers do not have high specificity, they are useful in suggesting the location of the primary focus, such as lung tumor-related antigens (NSE, CEA and CyFRA211), breast tumor-related antigens (CEA and CA153) and genital tumor-related antigens (β-HCG, AFP and CA153). For patients with suspected brain metastases, chest X-ray and abdominal and pelvic ultrasound were performed. For those with positive results requiring further clarification and those with negative results but still suspected brain metastases, CT scan and enhancement of the chest, abdomen and pelvis were added. If the primary lesion is not found in the routine examination but brain metastasis is highly suspected, whole-body 18FDG-PET examination will be performed. Treatment of brain metastases Surgical treatment of brain metastases is used for: (1) patients with single or multiple brain metastases with obvious local occupying effect and possible brain herniation; (2) patients with single brain metastases located at surgically accessible sites, in good general condition (KPS>70) and stable extracranial tumors. For these patients, surgery combined with postoperative whole-brain radiotherapy can improve the intracranial local control rate, and the effect is better than surgery alone or whole-brain radiotherapy alone; (3) Patients with intracranial lesions suspected to be metastases, and the pathological diagnosis cannot be obtained extracranially, stereotactic biopsy surgery or open biopsy surgery is feasible. Radiation therapy for brain metastases includes whole-brain radiotherapy and stereotactic radiosurgery. Whole brain radiotherapy is still the standard of care for brain metastases. It is used for: (1) single brain metastases after surgical resection or stereotactic radiosurgery; (2) single brain metastases with generalized tumor spread, poor general condition (KPS < 70) and life expectancy less than 3 months; (3) patients with multiple intracranial brain metastases. High intracranial local control rate. Chemotherapy is currently not the treatment of choice for brain metastases, but can be used as an adjuvant in some patients.