What should one do to treat cancer ??

It depends: Depending on the type of cancer -- there are hundreds, if not thousands -- and how far it's gotten, the modalities that may work are surgery, radiation, and/or chemotherapy. Anything else is "adjunct only" and if someone refuses mainstream therapy, the cancer will kill them unless something else does first. Some cancers are not treatable for cure, but may be palliated. Best wishes.