If you had the cure would you care about the industry? Honestly, you can make a mint and your name will go down in history. What would be the motivation for the person with the cure for cancer not to become a rich worldwide hero?
You would want to publicize your cure—but then you would meet the AMA and FDA (ah, but I repeated myself :-( ) and get to know them really well...
Large institutions want to perpetuate their existence and grow larger—it is not in their interest to cure disease.
the “premise” of this conspiracy theory is that the drug companies already found it, and are covering it up...
Of course for this to be true means that the actual individuals who were involved in the discovery keep their mouths shut...
So, someone discovered the cure in a drug companies lab, the execs decide we make more money selling drugs to treat so lets not make money selling things that cure... so squash the research and kill off the scientists who discovered it, oh, and then to be sure no one ever talks, need to kill off the people who decided to kill off the scientists too...
Honestly, my bet is that cancer treatment will likely end up being like this doctor is proposing... eventually will be like HIV treatment... lifetime of drugs, to keep the cancerous cells in check.. as there is no way to truly guarantee not one single cancerous cell remains.