Blood tests for testing cancer markers during therapy are already standard since a long time. A family member of mine got that testing regularly about 10 years

Blood tests for testing cancer markers during therapy are already standard since a long time. A family member of mine got that testing regularly about 10 years ago but the predictive value was not good. Still, if the accuracy improves it's a good development and could be revolutionary once high enough since some types of cancer are very likely to be curable if detected early enough. But yes, a false positive result can make things worse, especially for people that are in a risk group.