My husband is currently being treated for a recurring tumor, Glioblastoma stage IV, initial diagnosis was almost 4 years ago in June of 2007. Recurrence diagnosed in January was treated with cyberknife and subsequently and currently with Avastin. He is in really bad shape, even with treatments, no appreciable quality of life. I asked his physician what to expect if we were to opt out of treatments and he responded there would be an approximate 2 month life expectancy. With 20 plus various types of brain tumors, I would guess that there at least that many different ways to respond to your question. Life expectancies are merely statistical averages. So when a doctor told me he would most likely survive 6 months, that means some patients die in a month, others in one year. That is a wide spread. A four year GBM survival rate is almost unheard of. Best of Luck.