I don't see how something like high dose vitamin C IV is very expensive. I would assume a handful of oncologists could do the whole thing themselves. We get X patients a year, we randomly suggest the vitamin C IV to half, the half with vitamin C did better or worse by these metrics. Vitamin C is not expensive and they have to collect the outcome data for everyone involved anyway - so where is the expense coming from?
If it has benefits then more doctors will start to do it and more data will become available. If not, onto the next thing.
If it has benefits then more doctors will start to do it and more data will become available. If not, onto the next thing.