Liquid biopsies like Grail can be used clinically post-diagnosis to detect residual cancer cells and inform treatment decisions.

“the whole Advantage the idea of this is um we have to be careful that we're not overt treating cancer and of course we're not undertreating cancer so right now we overtreat a lot of patients because we're not sure if they have any uh remaining disease but we just want to be sure and so they get all these treatments that they ultimately didn't end up needing so one of the advantages of this testing uh on the post- treatment side of things is if there is no evidence of any circulating tumor cell circulating tumor DNA we can potentially deescalate the treatments and say you don't need any further treatments right now”