Colon Cancer in Eldery

Hey, my grandpa was experiencing blood from his stool to the point where he was pooping pure blood. He was just diagnosed with colon cancer, stage unknown. He is 86 years old, and has been in good health. Can anyone help me understand more about what he has? I'm worried he will die as he is old and harsh treatments may not be an option... Does anyone know the mortality rate? Or an estimate for a man in his age and condition?? Thank you...