If a brain tumor is a malignant tumor in the brain, and it is the most malignant grade IV glioma, the prognosis is quite poor. Even if surgery plus radiotherapy and chemotherapy is taken, its average survival is only about 12-14 months. Even with surgery plus radiotherapy and chemotherapy, the average survival time is only about 12-14 months. If there is no surgery, but only radiotherapy and chemotherapy, the average survival time is only about 3-6 months. How long one can live after radiation and chemotherapy for brain tumor depends on the malignancy of the brain tumor, the degree of surgical resection, and the age of the patient and other factors. If the malignancy of the tumor is high, the surgery is not fully resected or there is no surgery, and the patient is older, the survival period will be shorter. If the tumor is less malignant, the surgery gives total resection, and the patient is not too old, the survival period will be relatively longer.