I've never heard of any danger of chemotherapy aside the usual side-effects. Certainly never heard of an allergic reaction.
I would imagine the problem of the lack of reporting on such risks of the chemo drugs is that chemo drug production is controlled by big Pharma companies who have billions of dollars in a legal war chest, and it is rather well known that anyone who publishes any kind of report into the dangers of a commercial drug will get sued to hell and back for libel, regardless of the evidence in favour of them. The few drugs that have been successfully taken off the market are the really, really bad ones like thalidomide, and even with that people were scared of publishing the danger of that drug because of the likely legal action that would follow.
So yeah, unless you can afford to conduct a comprehensive study into the chemo drugs, and then afford the legal action that would follow, then you can't do anything about it.
Big Pharma controls governments.