My dad is 97 years old. He has had prostate cancer for about 10 years. He was diagnosed with stage 4 prostate cancer about 6 months ago. He can barely walk, he is weak, he doesnt eat or drink much . He is disoriented at times. He has bathroom accidents and a reoccuring urinary tract infection that is relentless. His whole mental state changed. He sleeps most of the day.He also spits alot. We dont know why but he does. I was wondering what is the life expectancy?