I certainly do not have the answer since my cancer did come back. Most books and web sites focus on DIET and NUTRITION although since most foods cannot be patented nor need a prescription, no "gold standard" testing is done that would meet medical standards of "proof". But having a good diet and getting lots of exercise is a good idea even if you never had cancer. I had thought the answer was Eat, Pray, Love, but now I'm down to Pray & Love. Working so far.
Hope you don't join the recurrence club
Keep the Faith
Charm