Intracranial metastasis (also called brain metastasis A) refers to the transfer of tumor cells originating in other parts of the body into the skull, and its incidence accounts for 3.5%-10% of intracranial tumors. It is believed at home and abroad that brain metastasis of lung cancer is the most common, followed by melanoma, genitourinary tumors and digestive tract tumors; there are also quite a number of patients in whom no primary foci can be found, and even if there is brain metastasis, the source of the tumors still cannot be determined after surgery. The peak age of onset is 20-50 years old, and there are more males than females. Disease Overview Brain metastases account for 10%-15% of intracranial tumors, and about 30% of malignant tumor patients are found to have brain metastases in autopsy. Brain metastasis of tumor origin is common in lung, breast, gastrointestinal tract tumor and kidney cancer, among which lung cancer brain metastasis accounts for 30%-40%, with small cell lung cancer and adenocarcinoma as the most common, some articles report that small cell lung cancer, if the survival period is more than two years, the brain metastasis rate reaches 80%.