It should be grade IV (not stage IV), most likely glioblastoma multiforme (GBM). There are other grade IV brain tumors with slightly better treatment outcome, but less common. If it is GBM, without treatment, the average survival is about 4 months; with surgery, radiation and chemotherapy(Temozolomide) , average survival is 12-14 months. In the past, the 5 year survival was about 0, now it is 9-10%.
This is one of the worst malignant tumors in human beings.