It would be worth reading the book by Dr Myers, "Beating Prostate Cancer; Hormonal Therapy & Diet", &/or his book "Eating Your Way To Better Health".
Briefly, Dr Myers suggests a heart healthy med diet and various supplements, for example Lycopene, selenium, vitamin E soy, vitamin D3.
The immune system can be helped in various ways: I take a mixture of olive leaf extract, atragalus and mushroom.