Well horrible as his (and you) situation is, should anything nasty rear its head you will already be at the top of the treatment page and not starting from scratch with doctors trying to find out what the problem is.
My own daughter had bowel (well, colorectal) cancer which resulted in a colostomy at 38 and her older brother has polyps and because of her cancer he too is regularly checked which, given their history is a relief.
I hope you get some joy out of Christmas and can put it to one side for the period, although I appreciate that it won't feel very joyful to either of you.
Best Wishes
Sandra