This is an area of general well being now with many schools of thought. It is wise to realise that Doctors are not Nutritionists and vice-a-versa.
There are now many “authoritative” books out now on foods to eat to prevent and reduce cancer and generally for a healthier life. One such is:-
The Plant Programme
Recipes for Fighting Breast and Prostate Cancer
Prostate Cancer – Understand, Prevent and Overcome…
By Professor Jane Plant
Any of her other books also.
A search on the web for “Food Books for Prostate Cancer” or some such will provide a whole host of books.
Some foods that are specifically beneficial for Prostate Cancer:-
Tomatoes – rich in Lycopeine, thought to be greater when cooked.
Some foods that are to be avoided with any cancer:- Sugar and Dairy
For a useful introduction to Nutrition click here.
There is some value in using herbs to treat many diseases, a good starting point for information is here.
For those of who would like to explore the many ways of natural treatments, a good start can be made here.