Liquid biopsies should be compared to current screening tests for cancers, and their use requires careful consideration if they are worse.

“in the cancers that that we already have screening tests for i think it's really important how the tests compare to the existing screening tests obviously if they're as good or better than what we're already doing well then you could argue well then we should switch to those right even if they're not perfect but um but if they're worse which is currently the situation the liquid biopsies aren't as good as those tests then you really have to think hard about how you would use them”