That would definitely be a bonus, re mets, @Blossom1961 .... there are already 'cancer markers' in regular blood tests, but they are not specific to BC. My husband had them regularly for the first 5 years after most of his stomach was removed back in 2010.
I reckon it would be a while before mammograms were 'done away with' and replaced by a blood test ..... even the prostate blood test has been known to be fairly erratic, as it is also hormone fed (as I understand it) and can change from day to day.
There is also this one that is being worked on as well, specifically aimed at identifying mets sooner ...
https://www.sciencedaily.com/releases/2019/09/190910134313.htm?fbclid=IwAR1d7wKZB7uViXBzx2O5Tb6gTmYfdCItkEuumhDswP2QxSJxXevLSmR--10I think I found it ....
https://www.telegraph.co.uk/news/2019/11/03/simple-blood-test-could-spot-breast-cancer-five-years-symptom/take care xxxx