You’d need to run a double blinded randomizes controlled trial with enough patients to test the effect.

And it would be wildly unethical to use prayer which by any reasonable understanding of cancer biology would not work.

Why does it have to replace therapy? One arm can be prayer + therapy and another can just be therapy

Ok, that would address the unethical part, but still, does that sound like a good use of limit research dollars?

This is one of those instances where judgement is a good thing. Don’t run such a silly trial. Spend the money on something that actually has a chance to work.