This ignores the way markets actually work.
You are quite correct that a cheap, easy and simple cancer cure would upset a lot of gravy trains.
However, any one of the big powerful drug companies that acquired or licensed the rights to the process would make a great deal of money, while damaging its competitors.
So the "coverup" theory is based on the notion that each and every one of the drug companies will do what's good for the industry as a whole rather than what is good for that particular company.
Things don't work that way. Any company will cheerfully, even gleefully, destroy its entire industry if it is its own best interest.
I just watched that Burzynski movie on the recommendation of a physician friend. I found it very interesting, provocative, and frankly upsetting. We were both discussing the embedded institutional corruption of our nation and whether we would ever see revolutionary cures come about in our lifetime. There are massive conflicts of interest that currently exist between regulators and the healthcare industry. There are massive profits being made to maintain the status quo and the FDA is on their payroll as the movie illustrated.
The FDA tried for years to block him, and then they collaborated with Elan?? to steal his patents on antineoplastons.
The researcher from the National Cancer Institute had a good suggestion that all government cancer research money should be divided into two parts one for establishment big business approved treatments, and the other for the alternative medicine? At the end of the year the money would be reconfigured based upon successes.
I’m now cynical enough to believe if someone ever developed a 300 mpg carburetor, it would never see the light of day because of the embedded wealth it would destroy. The same outlook with revolutionary cures.