The mineral selenium is one of the best cancer fighters there is. It is not only a good antioxidant but it also renews your glutathione which you body makes but as we age it gets depleted. You can find good information at
Other antioxidants vitamin C,A and E, green tea grape seed extract. Foods like tomatoes especially prostrate cancer.
Changing your cooking habits - no fried foods, no oils, no margarine, no mayo. All contain trans fatty acids that promote cancer.
Dr Otto Warburg got a Nobel Prize in 1931 showing that cancer needs an acid environment and a lack of Oxygen to survive. He said he could make any cell cancerous by depriving it of oxygen and reverse if by giving it oxygen.
So if you keep your body alkaline and have a good oxygen in your blood your are on your way for being cancer free