I think many doctors avoid the "x-months to live" scenario so that 1); patients won't focus on it; and 2) because it can very so much due to individual response to treatment. None of my physicians mentioned "x-months" until I asked point-blank.
I was diagnosed with non-small cell lung cancer Stage IV (mets throughout the body, skeletal system and brain) in October of 2003. I have been truly blessed in that I suffer no pain or dysfunction because of my disease. I only have side affects from the treatments. 8-)
Now, twenty months later the overall picture hasn't changed. I still have mets where I did originally, and the cancer is not in remission, but is "almost stabilized". I say "almost" because no treatment has totally eradicated the primary tumor, and without treatment, my CEA level slowly rises at a rate of about 10-15% a month.
Back to your question. My original "odds" were less than 5% of surviving two years. Statistically, my current odds are less than that because the original tumor was never alleviated. But you can also say that my odds are higher because I've had no ill effects and because the disease has not "spread".
The odds are impossible to determine. Age, health, genetic makeup and patient response are upredictable. Use the statistics to plan for you children, then forget the numbers, and get on with living, even if it's only day by day.
God bless.