There is a lot of quackery going on.... and people who are dying and have exhausted all the known legitimate options are especially likely to be desperate.
(Could we draw a parallel to audiophiles who are desperate to improve their systems - and feel nearly as strongly about the need to do so?)
As for cancer cures containing cyanide...
There is something deeper going on there...
Quite a long time ago there was a cancer cure called Leatrile which was a very popular subject of the conspiracy buffs.
Leatrile was very thoroughly outlawed in the USA after it was found to produce no useful benefits AND to be extremely toxic.
Fans claimed that "Leatrile would cure cancer but the government, or the big pharma companies, had conspired to suppress it".
Part of how it "worked" was that the chemicals it contained broke down in the human body to release cyanide.
Note that, by itself, the presence of cyanide is not necessarily bad, peach pits and apple seeds contain cyanide, and some chemicals may be poison in certain qualtities, but beneficial in others.
Therefore, the presence of cyanide in small quantities by itself doesn't mean much.
However, the "deeper aspect" I alluded to was this:
After Leatrile was banned, many quacks attempted to get around the ban by devising "other formulations that did pretty much the same thing but avoided the banned formulation".
So, the presence of cyanide in a quack cancer cure, beyond being unlikely to be beneficial, is often taken to suggest that "it's yet another Leatrile knockoff".
You will find similar, but probably harmless, cures based on the idea that "inflammation" causes most illnesses... and can be cured by drinking prickly pear cactus juice...
And, a few years ago, the big obsession was "antioxidants"...
It would be hard to isolate any positively effective alternative drug/supplement vs all the negative ones. I already brought up B17: many have been selling it as a cancer cure, when it can contain cyanide. I recently became aware of a complete loon, Jillian Mai Thi Epperly, who preys on the sick by trying to sell a protocol of drinking cabbage juice with heavy doses of sodium (It's called Jilly Juice). She was on Dr Phil, and showed she has no medical background. She claims her protocol cures everything because she's riding the body of Candida fungus (and claims that Candida is the root of all illnesses: she even claims homosexuality is an illness). When Dr Phil asked what study she's done for her claim that Jilly Juice can even regrow limbs, her response was "I have all my limbs". Because her followers are exposing themselves to sodium toxicity, they get severe diarrhea and high blood pressure. Unfortunately, a lot of people who are preyed upon are in desperate situations. I've known a few people who decided to forego traditional medicine and try naturopath for curing their cancer.
