In most medical studies, there are three outcomes for medicines which are determined to work: the best, which is from the medicine being tested; some effect, achieved with placebos; and no effect, which comes from the control group.
With a placebo it is assumed you are giving nothing, but this is not true: it is more or less literally a means of giving BELIEF, and of organizing the bodies systems in a way we really don’t understand in the service of the chosen aim.
The existence of the Placebo Effect should be much more researched than it is. Almost all of them do something, and it doesn’t really matter what illness is supposedly being treated. I am far from the first to find this fascinating.
As one obvious idea that has no doubt occurred to someone, why not give placebos for illnesses for which we have no cure? I am sure some professional medical ethicist could make that work. You increase the chance of life. You incur no risk of harm if you are not substituting the placebo for something which might have worked better.