Chiron,
I agree with your message where a plant-based whole-food diet acts as a prophylactic against cancers and other chronic diseases; that is all very well for those who have not contracted the disease, but where cancer has already taken hold, individual elements of nutrition can be a life saver. One only has to consider the Budwig protocol where its mainstay is Quark or cottage cheese mixed with flax-seed oil.
Ascorbate in megadoses, and delivered intravenously is another.
Many do not lead lifestyles or have dietary habits in order to prevent cancer, so education is the key in prevention, but in the meantime, targeted nutritional methods are sometimes the only answer.