Please provide your extraordinary evidence. Ideally in the form of multiple strong, well-vetted and well respected studies in peer-reviewed journals. Otherwise I'll presume you're full of it.
What is the first claim though? Is it that extraordinary evidence needs to be provided for the claim that a poison (chemotherapy) is a cure for cancer?
You will likely say that there is evidence in "multiple strong, well-vetted and well respected studies in peer-reviewed journals".
But then I would question the authority of peer-reviewed journals. Do know about replication crisis?
https://www.bbc.com/news/science-environment-39054778 : "According to a survey published in the journal Nature last summer, more than 70% of researchers have tried and failed to reproduce another scientist's experiments."
https://en.wikipedia.org/wiki/Replication_crisis : "a number of efforts have been made to re-investigate classic results, to determine both the reliability of the results and, if found to be unreliable, the reasons for the failure of replication."
Another reason I dismiss most scientific authority is on account of funding. If funding is controlled by government, the military and private corporations (as it is), then this triad can cooperate to fund or de-fund whatever studies they like.
To see what I mean about funding, we can look at my imagined idea that 'you want to prove the health benefit of cold potatoes'. First you can fund 10 studies. Let's say 2 support the thesis, 2 refute it and 6 are inconclusive. You can then further fund the 2 that support it. And rinse and repeat. Pretty soon you could have enough studies to create a whole new field exclaiming the wonder of cold potatoes.
Unfortunately, this really is how science works. Science is a money making operation, and is politicised. A common sense idea like fasting for cancer, or not eating carbohydrates to get rid of diabetes, has no economic benefit. Scientists themselves can work within the system with good intentions, but can be more or less unaware of the machinations and agendas at play.
If you want to talk about solutions, you would take a totally different tack. At present we have a sickness not a wellness industry. Companies get money from you when you are sick. The more sick you are, the better it is for their monetary return. The ideal patient is someone who will be ill for a long time, which is a perverse incentive. Really, you want a wellness industry, where if you are well, those ensuring your health get paid. As they are incentivised to keep you well, you should expect good advice - their financial well-being depends on it.
Let's start by not conflating all kinds of cancer and all kinds of chemotherapy, because it's not a single disease, and the outcomes vary greatly.
But, for instance, survival rates for testicular cancer have risen significantly (or even dramatically) since the invention and introduction of the chemotherapy treatment that is being used for it today. If detection isn't overly delayed, the cure rate in the developed world today is around 95 to 100 percent.
So let's please, please, please, not go for cheap "chemotherapy = poison" rhetoric. I have first-hand experience with the adverse effects, but you can't dismiss a nearly 100% cure rate.
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Regarding what you more generally wrote, it's true that financial interests affect and direct the pharma industry. There are several adverse effects from that, such as research not being directed at areas with potential health benefits but low profitability, and also over-marketing (and thus possibly over-prescription) in other areas. It would also be great if medical research were less tightly bound to funding from the industry and rather got its funding from public sources instead. (That wouldn't make it non-politicized, but direct financial interests might not be as significantly involved.)
But it would be rather misguided to think that there aren't actual working treatments coming out of the industry and research as well. Sometimes those treatments are the difference between life and death. Let's not discount that.
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The significantly improved survival rates for TC are pretty well-known, but a couple of sources:
https://en.wikipedia.org/wiki/Testicular_cancer#Prognosis
https://jamanetwork.com/journals/jama/fullarticle/181433
https://ascopubs.org/doi/full/10.1200/JCO.2014.56.0896
edit: line breaks between URLs
But even so, it would be interesting to see numbers anyway.
Obviously, I'm joking.
But did you know that iatrogenic deaths - deaths caused by doctors - are the 3rd largest cause of death in the US?
And when you see the numbers, bear in mind that these are only the official reported numbers! I can only imagine how many other deaths must be caused by doctors but get explained as natural deaths.