You might be getting ahead of yourself a bit. Let doctor treat the disease and see what happens. As to fear and worry, ever notice how many of your worst fears never actually happened? Have confidence in doctor and take one day at a time. If you still have doubts, have another doctor review the case. In the meantime, enjoy each and every day to the fullest, since we are given only one day at a time to live.
I know of a 95 year old woman who underwent both radiation and chemo for multiple myeloma and is doing rather well.