Ok, taking religion out of the equation here is what I know from what I have witnessed personally ( my husband is batteling two different forms of cancer) and educationally ( I am pre med)
I can not tell you how long patients have, and neiter can a MD of Oncology. Every patient is different. This does not appear to be helpful, i am sure. But there are literally patients that have been told that you may have 6months to live, and in 5 months they do all that they can to make ammends, tie up loose strings, etc... and w/ a month left they just stop and focus on this is it and they sucome. and then there are the patients that are told the same thing, ans say " i dont have time to die", and they dont!, they live for years beyond the time tabe they were given.
Cancer is a very personal battle for eveyone. There are no two identical cases that end exactly the same way. What you need to find out is what cell type of cancer does he have, is it indolent meaning slow growing, or is it advanced. what are teh best measure to insure quality of life over quantity, and are there support groups that both of you could get involved in.
I do understand your wanting to take religion out of the equation, but i want to share something w/ you that one of my professors told me" all the data , and all the stats we have on terminal patients do not count the unexplainable things that sometimes happen". Your beliefs are your choice, and its ok, just understand that sometimes the patient needs to have faith in something, anything.