When it's killing you? My brother has a benign tumor which was growing around his brain stem, it drastically affected his cognitive ability, personality, vision and the things we take for granted like breathing, swallowing, seeing. He was told that he was at the point where if they did nothing he would die, the flip side being that if they did do something he might still die. He had the surgery but stroked out on the table, he was revived but there were grave consequences like sight only in one eye and of very narrow range, impaired use of one side, speech impairment and a changed personality. But hey he survived, except the part of the tumor remained and it is only a matter of time until it grows and succeeds in killing him.