I was quite surprised to see this question at +4 score:
It doesn't seem to show any initial research before asking a question. The question is too broad in this particular case and even if it wasn't: Do questions about best cures on diseases really belong on Biology.SE? If they do, is the community aware what content does the topic of best cures attract?
There is generally two problems with this sort of question:
1) Is it medical advice? /Could the answer be used as medical advice?
2) How do we measure "best"?
Additionally, I consider these questions highly trivial with little research effort - there's no attempt to understand biological concepts, or why and how certain treatments affect differently, so we could close them as off-topic (but there isn't a consensus view on this yet).
I think we can most often close these sorts under the primarily opinion based close vote, as the best treatment is extremely subjective - one has to decide whether to consider the efficacy, side effects, financial costs, ethical costs in manufacture and development.
As an analogy, one might ask "how do I best count the number of individuals in a bird population?" and the answer would depend on the population being measured*, and whether best is the the cheapest, the quickest, the most consistent, the most feasible, or the most accurate, or any balance of all those variables?
* To bring that point back to the question, the best cure will depend on the type of cancer, just as the best method for counting birds depends on the characteristics of the study population (size, terrain, movement, density..). Thus the question would also be too broad.
I think treatments of diseases fall under the broad category of "Biology" so these questions can be on-topic. However, "best" is a subjective term. This question, and any other questions like it, should probably be rephrased as "What is currently the most widely-used cure" or something similar.
As long as the person asking a question is not doing this for his personal benefit (which would be classified as a personal medical question and thus be off-topic) I don't think this is a major problem. It can be argued that such questions can be too broad, but I think they are not off-topic per se.
Additionally we can take measures (e.g. close them fast) if naturopathic questions of that kind show up. We had a few of these before - they never posed a real problem.
