Clinically, it is more difficult to cure brain metastatic cancer with Gamma Knife. Most of the brain metastases will be reduced after Gamma Knife treatment, the clinical symptoms of patients will be reduced, and the survival time of patients can be prolonged, but it is generally difficult to completely cure brain metastases. Gamma knife treatment is a kind of radiation therapy. Because of its simple operation, no anesthesia before treatment, fewer side effects after treatment, no surgical trauma, and low requirements for patients’ physical condition, it is commonly used in advanced cancer patients with multiple brain metastases who cannot be treated by surgery. However, because brain metastases are advanced lesions, Gamma Knife is only a local treatment means, which is less effective in controlling patients’ systemic diseases, so it generally cannot cure brain metastases. Gamma Knife is generally used for intracranial metastases with a small number of metastases and metastatic tumors with a diameter of 3cm or less. The tumor at the irradiation site can basically be killed, but generally cannot do prophylactic irradiation.