> My impression is that people successfully market products like this to give people a sense of control where given the state of the art, control is lacking. T

> My impression is that people successfully market products like this to give people a sense of control where given the state of the art, control is lacking. There can be no such evidence for a screening method like this, because it is brand new. We may find that even detection as early as Grail provides is still insufficient, but we don't and can't know yet. Certainly with many cancers earlier detection does lead to better outcomes. You also seem to be focusing on cases where screening has not improved outcomes while ignoring cases where it has.