My Partner Was 65 When He Developed Throat Cancer. He

My partner was 65 when he developed throat cancer. He had his voice box operated on and they removed the cells and he now has a weak voice, but a voice... He had radiation but not chemo. That was 5 years ago. Particularly in the last 2 years, his behaviour has altered, he fumbles, shuffles, forgets things, drops things, constantly mistakes requests and cant seem to do the simple things he has always done as a matter of course. He even looks older and seems to be getting more house bound etc.